--------------------------------------------------------------------------------
Prospectus
                                    XOMA Ltd.
                             3,868,395 Common Shares
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o    All of the common shares covered by this prospectus are being offered by
     Genentech, Inc. and have been previously issued to Genentech or will be
     issued to Genentech by XOMA upon conversion of the preference shares held
     by Genentech.

o    We have used the proceeds from the common shares previously issued to
     Genentech covered by this prospectus and the convertible subordinated debt
     issued to Genentech, which was repaid in part with the issuance of
     preference shares that are convertible into common shares covered by this
     prospectus, for the development of RAPTIVA(TM), a humanized anti-CD11a
     monoclonal antibody, in collaboration with Genentech.

o    The preference shares issued to Genentech that are convertible into the
     common shares covered by this prospectus repaid a portion of the
     convertible subordinated debt issued to Genentech. We have benefited from
     this cancellation of indebtedness.

o    Genentech will receive all of the proceeds of its sale of such common
     shares to you.

o    Our common shares are listed on the Nasdaq National Market under the symbol
     "XOMA." The last reported sale price for the common shares on January 20,
     2004 was $7.18 per share.

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     This investment involves a high degree of risk. Consider carefully the risk
factors beginning on page 5 of this prospectus before you invest.

                              ____________________

     Neither the SEC nor any state securities commission has approved these
securities or determined that this prospectus is accurate or complete. Any
representation to the contrary is a criminal offense.

                              ____________________

                   The date of this prospectus is May 7, 2004.









                                TABLE OF CONTENTS


                                                 Page                                                        Page
                                                 ----                                                        ----

                                                                                                      
PROSPECTUS SUMMARY................................2           USE OF PROCEEDS..................................20
RISK FACTORS......................................5           SELLING SHAREHOLDER..............................21
INCORPORATION OF INFORMATION                                  DESCRIPTION OF SHARE CAPITAL.....................23
  WE FILE WITH THE SEC...........................17           PLAN OF DISTRIBUTION.............................26
SPECIAL NOTE REGARDING                                        LEGAL OPINION....................................27
  FORWARD-LOOKING STATEMENTS.....................18           EXPERTS..........................................27
PRICE RANGE OF COMMON SHARES                                  WHERE YOU CAN GET MORE INFORMATION...............27
  AND DIVIDEND INFORMATION ......................19









                                      -i-



                               PROSPECTUS SUMMARY

XOMA

     We are a biopharmaceutical company that develops and manufactures
recombinant antibodies and other protein products to treat cancer, immunological
and inflammatory disorders, and infectious diseases. Our current product
development programs include:

o    RAPTIVA(TM)(Efalizumab) is a humanized anti-CD11a monoclonal antibody
     developed to treat immune system disorders. In October of 2003, the FDA
     approved RAPTIVA(TM) for the treatment of chronic moderate-to-severe plaque
     psoriasis in adults who are candidates for systemic therapy or
     phototherapy. Genentech has granted Serono S.A. exclusive marketing rights
     to RAPTIVA(TM)outside the U.S. and Japan. In February of 2003, Serono
     announced the filing of an application for European Union marketing
     approval of RAPTIVA(TM)in moderate-to-severe plaque psoriasis.

     In January of 2003, we announced initiation of a Phase II study to evaluate
     RAPTIVA(TM) as a possible treatment for patients with psoriatic arthritis.
     Genentech and we continue to assess additional indications for RAPTIVA(TM).

o    In December of 2003, we and Alexion Pharmaceuticals, Inc. agreed to
     collaborate for the development and commercialization of an antibody to
     treat chemotherapy-induced thrombocytopenia. The c-MPL antibody was
     designed to mimic the activity of human thrombopoietin, a naturally
     occurring protein responsible for platelet production.

o    Millennium Pharmaceuticals, Inc.'s biotherapeutic agent, MLN2222, also
     known as CAB-2, is being developed to reduce death and heart attacks in
     patients undergoing procedures involving cardiopulmonary bypass surgery
     pursuant to a collaboration agreement with Millennium that was announced in
     November of 2001. In December of 2003, we announced the initiation of Phase
     I clinical testing of the compound.

o    XMP.629 is a BPI-derived topical anti-infective compound that is in
     preclinical testing as a treatment for acne. In September of 2003 and
     January of 2004, respectively, we announced the initiation of Phase I and
     Phase II testing.

o    NEUPREX(R), also known as rBPI21, is a genetically-engineered fragment of a
     particular human protein. We completed a Phase III efficacy clinical trial
     in 1999, testing NEUPREX(R)in severe pediatric meningococcemia, but the
     data from the trial were determined not to be sufficient to file for
     regulatory approval. Further development of this product continued under a
     license agreement with a division of Baxter Healthcare Corporation, and a
     Phase II study testing NEUPREX(R)in Crohn's disease completed enrollment in
     November of 2002. In July of 2003, our licensing arrangement with Baxter
     for NEUPREX(R)was terminated, and the rights returned to us. In October of
     2003, we and Children's Medical Center Dallas announced the initiation of
     clinical testing of NEUPREX(R)in pediatric open heart surgery patients.
     Future development plans are under review.

o    We are developing BPI-derived anti-angiogenic compounds with potential
     application for treating retinal disorders. Results of in vitro and in vivo
     studies conducted by Joslin Diabetes Center at Harvard University,
     presented in April of 2001 and published in February of 2002, showed that
     compounds derived from BPI inhibit the function of multiple growth factors
     involved in blood vessel formation and angiogenesis in the retina while
     sparing key retinal cells (pericytes). These data suggest that these
     compounds may have potential for treating retinal disorders. We are
     conducting further research together with Joslin.

o    ING-1 is a Human Engineered(TM)recombinant monoclonal antibody that binds
     with high affinity to an antigen expressed on epithelial cell cancers
     (breast, colorectal, prostate and others) that is designed to destroy
     cancer cells by recruiting the patient's own immune system. Enrollment has
     been completed in two Phase I studies testing intravenous administration in
     advanced adenocarcinoma patients, which showed safety and tolerability
     results that supported further clinical development. An additional Phase I
     study with subcutaneous administration showed similar results. Further
     product development efforts will depend on future collaborative
     arrangements. The ING-



                                      -2-


     1 monoclonal antibody incorporates our patented Human Engineering(TM)
     technology, designed to reduce immunogenicity.

     We have experienced significant losses and, as of September 30, 2003, we
had an accumulated deficit of $580.0 million. For the nine months ended
September 30, 2003, we had a net loss of approximately $39.0 million, or $0.54
per common share (basic and diluted). For the year ended December 31, 2002, we
had a net loss of approximately $33.2 million, or $0.47 per common share (basic
and diluted). We expect to incur additional losses in the future, primarily due
to launch related sales and marketing expenses for RAPTIVATM, as well as
development costs related to the Alexion and Millennium collaborations and our
XMP.629 compound.

     Based on current spending levels, revenue estimates, net proceeds received
from our recent underwritten public offering, repayment obligations of our debt
owed to Genentech for our share of RAPTIVA(TM) sales, marketing and development
costs, outstanding loans from Genentech, issuance of shares in repayment of the
remainder of the development loan from Genentech and financing commitments from
Millennium under the collaborative agreement between the companies, we estimate
we have sufficient cash resources, together with sources of funding available to
us, to meet our current net cash consumption levels through at least the end of
2005. Continuing losses on RAPTIVA(TM) or any other significant revenue
shortfalls, or increases in planned spending on research, development or sales
and marketing programs could materially shorten this period. The recent FDA
approval of RAPTIVATM is expected to improve operating cash flow to the extent
of XOMA's share of operating profits from sales of RAPTIVATM in the U.S., but
requires repayment of amounts owed to Genentech under the financial arrangements
as discussed below. Our actual share of profits or losses from RAPTIVATM may
materially impact our cash balances. Additional licensing arrangements or
collaborations or other new equity or other financing arrangements could
potentially extend or shorten this period. We continue to evaluate alternative
financing arrangements to strengthen our overall financial position and mitigate
liquidity risks. For a further discussion of the risks related to our business
and their effects on our cash flow and ability to raise new funding on
acceptable terms, see "Risk Factors."

Material Terms Of Arrangement With Genentech

     In April of 1996, we entered into a collaborative agreement with Genentech
to jointly develop RAPTIVA(TM) for treatment of psoriasis and organ transplant
rejection. In connection with the agreement, Genentech purchased 1.5 million
common shares for approximately $9.0 million and agreed to lend us our share of
the development costs for RAPTIVA(TM) until the completion of Phase III clinical
trials and FDA approval. This funding was through the issuance of convertible
subordinated notes due at the earlier of April of 2005 or upon regulatory
approval of RAPTIVA(TM).

     On October 27, 2003, the FDA approved RAPTIVA(TM) for the treatment of
chronic moderate-to-severe plaque psoriasis in adults who are candidates for
systemic therapy or phototherapy. Under the terms of our financing arrangement
with Genentech, this approval triggered a 90-day period at the end of which the
convertible subordinated debt would have matured. For payment of the convertible
subordinated debt, we elected pursuant to the development loan agreement to
defer payment of $40.0 million as an offset against our proceeds from our 25%
share of U.S. operating profits on the product and to pay the remaining balance
(approximately $29.6 million) with preference shares before December 31, 2003.
These preference shares were issued in December of 2003 and are convertible into
an aggregate of 3,818,395 common shares at a conversion price of approximately
$7.75 per share.

     We have agreed to register the resale of the common shares that we may
issue to Genentech upon conversion of these preference shares. This prospectus
is intended to satisfy these registration obligations.

     The 3,868,395 shares covered by this prospectus consist of

o    50,000 common shares held by Genentech; and



                                      -3-


o    3,818,395 of our common shares into which the preference shares issued to
     Genentech may be converted based on the conversion price of approximately
     $7.75 per share

and in the aggregate would have represented approximately 4.6% of our
outstanding common shares as of January 20, 2004, after giving effect to their
issuance.




                                      -4-




                                  RISK FACTORS

     You should carefully consider the following factors and other information
in this prospectus before deciding to invest in our common shares. You should
also consider carefully the other information contained, or incorporated by
reference, in this prospectus. The actual results of our business could differ
materially from those described as a result of these risk factors. In such case,
the trading price of our common shares could decline, and you may lose all or
part of the money you paid to buy our common shares.

Risks Relating To Our Business

The Marketing And Sales Effort In Support Of Our Only Product To
Receive Regulatory Approval Has Only Recently Begun And May Not
Be Successful.

     RAPTIVA(TM), our only product to receive regulatory approval, was approved
by the FDA on October 27, 2003 for the treatment of chronic moderate-to-severe
plaque psoriasis in adults who are candidates for systemic therapy or
phototherapy. Genentech is responsible for the marketing and sales effort in
support of this product and has only recently commenced, and launched, the full
intended scope of this effort. Unless and until RAPTIVA(TM) is approved in this
or other indications outside the United States, our interest in this product in
this indication is limited to our 25% share of the operating profits from sales
of the product in the United States. We currently have no active role in this
marketing and sales effort. Successful commercialization of this product is
subject to a number of risks, including Genentech's ability to implement its
marketing and sales effort and achieve sales; the strength of competition from
other products being marketed or developed to treat psoriasis; physicians' and
patients' acceptance of RAPTIVA(TM) as a treatment for psoriasis; Genentech's
ability to provide manufacturing capacity to meet demand for the product; and
pricing and reimbursement issues. Many of these risks are discussed in more
detail below.

Because All Of Our Products Are Still Being Developed, We Will
Require Substantial Funds To Continue; We Cannot Be Certain That
Funds Will Be Available And, If Not Available, We May Have To
Take Actions Which Could Adversely Affect Your Investment.

     If adequate funds are not available, we may have to dilute or otherwise
adversely affect the rights of existing shareholders, curtail or cease
operations, or file for bankruptcy protection in extreme circumstances. We have
spent, and we expect to continue to spend, substantial funds in connection with:

     o    research and development relating to our products and production
          technologies

     o    expansion of our production capabilities

     o    various human clinical trials and

     o    protection of our intellectual property.

     Based on current spending levels, revenue estimates, net proceeds received
from out recent underwritten public offering, repayment obligations of our debt
owed to Genentech for our share of RAPTIVATM marketing costs, deferral of a
portion of our development loan from Genentech, issuance of shares in repayment
of the remainder of our development loan from Genentech and financing
commitments from Millennium, we estimate we have sufficient cash resources,
together with sources of funding available to us, to meet our current net cash
consumption levels through at least the end of 2005. However, continuing losses
on RAPTIVATM or to the extent we experience changes in the timing or size of
expenditures or unanticipated expenditures, or if our collaborators do not meet
their obligations to us or anticipated revenues otherwise do not materialize,
these funds may not be adequate for this period. In particular, our share of
profits or losses from RAPTIVATM may materially impact our cash resources. As a
result, we do not know whether:



                                      -5-


     o    operations will generate meaningful funds

     o    additional agreements for product development funding can be reached

     o    strategic alliances can be negotiated or

     o    adequate additional financing will be available for us to finance our
          own development on acceptable terms, if at all.

     Cash balances and operating cash flow are influenced primarily by the
timing and level of payments by our licensees and development partners, as well
as by our operating costs.

     Specifically, although the recent FDA approval of RAPTIVATM would generally
be expected to improve operating cash flow to the extent of XOMA's share of
operating profits from sales of RAPTIVATM in the U.S., such approval also
requires repayment in cash, shares or deferred repayment of up to $40.0 million
of amounts owed to Genentech (approximately $54 million under both loan
agreements as of December 31, 2003). In November of 2003, we announced our
election to defer $40.0 million of such repayment and to repay the remainder of
the development loan using shares. The commercialization loan is payable only in
cash and approximately $3 million is due in January of 2004 and approximately
$11 million is due in April of 2004. In addition, the receipt of regulatory
approval terminated Genentech's obligation to continue to loan us our portion of
development and commercialization expenses for RAPTIVA(TM).

Most Of Our Therapeutic Products Have Not Received Regulatory Approval.  If
These Products Do Not Receive Regulatory Approval, Neither Our Third Party
Collaborators Nor We Will Be Able To Manufacture And Market Them.

     Our products cannot be manufactured and marketed in the United States and
other countries without required regulatory approvals. Only one of our
therapeutic products has received regulatory approval. The United States
government and governments of other countries extensively regulate many aspects
of our products, including:

     o    testing,

     o    manufacturing,

     o    promotion and marketing, and

     o    exporting.

     In the United States, the FDA regulates pharmaceutical products under the
Federal Food, Drug, and Cosmetic Act and other laws, including, in the case of
biologics, the Public Health Service Act. At the present time, we believe that
most of our products will be regulated by the FDA as biologics. The FDA has
consolidated its responsibility for reviewing new pharmaceutical products into
its Center for Drug Evaluation and Research, the body that formerly reviewed
only drug products, combining that operation with part of its biologics review
operation, the Center for Biologics Evaluation and Research. Because
implementation of this plan may not be complete, we do not know when or how this
change might affect us. State regulations may also affect our proposed products.

     The FDA has substantial discretion in both the product approval process and
manufacturing facility approval process and, as a result of this discretion and
uncertainties about outcomes of testing, we cannot predict at what point, or
whether, the FDA will be satisfied with our or our collaborators' submissions or
whether the FDA will raise questions which may be material and delay or preclude
product approval or manufacturing facility ap-



                                      -6-


proval. As we accumulate additional clinical data, we will submit it to the FDA,
which may have a material impact on the FDA product approval process.

     Our potential products will require significant additional research and
development, extensive preclinical studies and clinical trials and regulatory
approval prior to any commercial sales. This process is lengthy, often taking a
number of years, and expensive. As clinical results are frequently susceptible
to varying interpretations that may delay, limit or prevent regulatory
approvals, the length of time necessary to complete clinical trials and to
submit an application for marketing approval for a final decision by a
regulatory authority varies significantly. As a result, it is uncertain whether:

     o    our future filings will be delayed,

     o    our studies will be successful,

     o    we will be able to provide necessary additional data,

     o    our future results will justify further development, or

     o    we will ultimately achieve regulatory approval for any of these
          products.

For example,

     o    in 1996, we and Genentech began testing RAPTIVATM in patients with
          moderate-to-severe psoriasis. In April of 2002, we and Genentech
          announced that a pharmacokinetic study conducted on RAPTIVATM
          comparing XOMA-produced material and Genentech-produced material did
          not achieve the pre-defined statistical definition of comparability,
          and the FDA requested that another Phase III study be completed before
          the filing of a Biologics License Application for RAPTIVATM, delaying
          the filing of a Biologics Licensing Application with the FDA for
          RAPTIVATM beyond the previously-planned time frame of the summer of
          2002. In March 2003, we announced completion of enrollment in a Phase
          II study of RAPTIVATM in patients suffering from rheumatoid arthritis.
          In May of 2003, we and Genentech announced our decision to terminate
          Phase II testing of RAPTIVATM in patients suffering from rheumatoid
          arthritis based on an evaluation by an independent Data Safety
          Monitoring Board that suggested no overall net clinical benefit in
          patients receiving the study drug. We have also completed enrollment
          in a Phase II study of RAPTIVATM as a possible treatment for patients
          with psoriatic arthritis. Although we expect to know preliminary
          results of the psoriatic arthritis trial by the first quarter of 2004,
          we do not know whether or when such testing will demonstrate product
          safety and efficacy in this patient population or result in regulatory
          approval. As is our practice, more details regarding the clinical data
          would be revealed at an upcoming medical conference or other
          appropriate scientific, peer-reviewed forum later in 2004.

     o    in December of 1992, we began human testing of our NEUPREX(R)product,
          a genetically engineered fragment of a particular human protein, and
          licensed certain worldwide rights to Baxter. In April of 2000, members
          of the FDA and representatives of XOMA and Baxter discussed results
          from the Phase III trial that tested NEUPREX(R)in pediatric patients
          with a potentially deadly bacterial infection called meningococcemia,
          and senior representatives of the FDA indicated that the data
          presented were not sufficient to support the filing of an application
          for marketing approval at that time.

     Given that regulatory review is an interactive and continuous process, we
maintain a policy of limiting announcements and comments upon the specific
details of the ongoing regulatory review of our products, subject to our
obligations under the securities laws, until definitive action is taken.



                                      -7-


Because All Of Our Products Are Still Being Developed, We Have Sustained Losses
In The Past And We Expect To Sustain Losses In The Future.

     We have experienced significant losses and, as of September 30, 2003, we
had an accumulated deficit of $580.0 million.

     For the nine months ended September 30, 2003, we had a net loss of
approximately $39.0 million, or $0.54 per common share (basic and diluted). For
the year ended December 31, 2002, we had a net loss of approximately $33.2
million, or $0.47 per common share (basic and diluted). We expect to incur
additional losses in the future, primarily due to increased sales and marketing
expenses related to RAPTIVATM, on the Alexion collaboration, the Millennium
collaboration and on our XMP.629 compound.

     Our ability to achieve profitability is dependent in large part on
obtaining regulatory approval for our products and entering into agreements for
product development and commercialization, both of which are uncertain. Our
ability to fund our ongoing operations is dependent on the foregoing factors and
on our ability to secure additional funds. Because all of our products are still
being developed, we do not know whether we will ever achieve profitability or
whether cash flow from future operations will be sufficient to meet our needs.

If Third Party Collaborators Do Not Successfully Develop And Market Our
Products, We May Not Be Able To Do So On Our Own.

     Our financial resources and our marketing experience and expertise are
limited. Consequently, we depend to a large extent upon securing the financial
resources and marketing capabilities of third parties with whom we collaborate.

     o    In April of 1996, we and Genentech entered into an agreement whereby
          we agreed to co-develop Genentech's humanized monoclonal antibody
          product RAPTIVATM. In April of 1999, the companies amended the
          agreement. In March of 2003, the companies further amended the
          agreement. In October of 2003, RAPTIVA(TM)was approved by the FDA for
          the treatment of chronic moderate-to-severe plaque psoriasis.

     o    In November of 2001, we entered into a collaboration with Millennium
          to develop two of Millennium's products for certain vascular
          inflammation indications. In October of 2003, we announced that we had
          discontinued one of these products, MLN2201. In December of 2003, we
          announced the initiation of Phase I testing on the other product,
          MLN2222.

     o    In December of 2003, we and Alexion Pharmaceuticals, Inc. agreed to
          collaborate for the development and commercialization of an antibody
          to treat chemotherapy-induced thrombocytopenia. The c-MPL antibody was
          designed to mimic the activity of human thrombopoietin, a naturally
          occurring protein responsible for platelet production.

     Because our collaborators are independent third parties, they may be
subject to different risks than we are and have significant discretion in
determining the efforts and resources they will apply. We do not know whether
Genentech, Millennium or Alexion will successfully develop or market any of the
products we are collaborating on.

     Even when we have a collaborative relationship, other circumstances may
prevent it from resulting in successful development of marketable products.

     o    In January of 2000, we licensed the worldwide rights to all
          pharmaceutical compositions containing a particular human protein for
          treatment of meningococcemia and additional potential future human
          clinical indications to Baxter. In July of 2003, this arrangement was


                                      -8-


          terminated, and the rights returned to XOMA. Although we are
          evaluating future options for developing this product, we do not know
          whether any options we may pursue will succeed.

     o    In January of 2001, we entered into a strategic process development
          and manufacturing alliance with Onyx to scale-up production to
          commercial volume of one of Onyx's cancer products. In June of 2003,
          Onyx notified XOMA that it was discontinuing development of the
          product and terminating the agreement so that it could focus on
          another of its anticancer compounds.

     Although we continue to evaluate additional strategic alliances and
potential partnerships, we do not know whether or when any such alliances or
partnerships will be entered into.

Because We Have No History Of Profitability And Because The Biotechnology
Sector Has Been Characterized By Highly Volatile Stock Prices, Announcements We
Make And General Market Conditions For Biotechnology Stocks Could Result In A
Sudden Change In The Value Of Our Common Shares.

     As a biopharmaceutical company, we have experienced significant volatility
in our common shares. Fluctuations in our operating results and general market
conditions for biotechnology stocks could have a significant impact on the
volatility of our common share price. From December 31, 2001 through January 20,
2004, our share price has ranged from a high of $12.19 to a low of $2.84. On
January 20, 2004, the last reported sale price of the common shares as reported
on the Nasdaq National Market was $7.18 per share. Factors contributing to such
volatility include, but are not limited to:

     o    sales and estimated or forecasted sales of products

     o    results of preclinical studies and clinical trials

     o    information relating to the safety or efficacy of our products

     o    developments regarding regulatory filings

     o    announcements of new collaborations

     o    failure to enter into collaborations

     o    developments in existing collaborations

     o    our funding requirements and the terms of our financing arrangements

     o    announcements of technological innovations or new indications for our
          therapeutic products

     o    government regulations

     o    developments in patent or other proprietary rights

     o    the number of shares outstanding

     o    the number of shares trading on an average trading day

     o    announcements regarding other participants in the biotechnology and
          pharmaceutical industries and



                                      -9-


     o    market speculation regarding any of the foregoing.

We Or Our Third Party Collaborators May Not Be Able To Increase Existing Or
Acquire New Manufacturing Capacity Sufficient To Meet Market Demand.

     Genentech will be responsible for manufacturing or arranging for the
manufacturing of commercial quantities of RAPTIVA(TM). Should Genentech have
difficulty in providing manufacturing capacity to produce RAPTIVA(TM) in
sufficient quantities, we do not know whether we will be able to meet market
demand. If any of our other products are approved, because we have never
commercially introduced any pharmaceutical products, we do not know whether the
capacity of our existing manufacturing facilities can be increased to produce
sufficient quantities of our products to meet market demand. Also, if we or our
third party collaborators need additional manufacturing facilities to meet
market demand, we cannot predict that we will successfully obtain those
facilities because we do not know whether they will be available on acceptable
terms. In addition, any manufacturing facilities acquired or used to meet market
demand must meet the FDA's quality assurance guidelines.

Because We Only Recently Received Approval For Our Only Approved Product And
We Do Not And Cannot Currently Market Any Of Our Other Products For Commercial
Sale, We Do Not Know Whether There Will Be A Viable Market For Our Products.

     Even though we and Genentech recently received FDA approval to market
RAPTIVA(TM) and even if we receive regulatory approval for our other products,
our products may not be accepted in the marketplace. For example, physicians
and/or patients may not accept a product for a particular indication because it
has been biologically derived (and not discovered and developed by more
traditional means) if no biologically derived products are currently in
widespread use in that indication, as is currently the case with psoriasis.
Similarly, physicians may not accept RAPTIVA(TM) if they believe other products
to be more effective or are more comfortable prescribing other products that
have been on the market longer than RAPTIVA(TM). Consequently, we do not know if
physicians or patients will adopt or use our products for their approved
indications.

Other Companies May Render Some Or All Of Our Products Noncompetitive Or
Obsolete.

     Developments by others may render our products or technologies obsolete or
uncompetitive. Technologies developed and utilized by the biotechnology and
pharmaceutical industries are continuously and substantially changing.
Competition in the areas of genetically engineered DNA-based and antibody-based
technologies is intense and expected to increase in the future as a number of
established biotechnology firms and large chemical and pharmaceutical companies
advance in these fields. Many of these competitors may be able to develop
products and processes competitive with or superior to our own for many reasons,
including that they may have:

     o    significantly greater financial resources

     o    larger research and development and marketing staffs

     o    larger production facilities

     o    entered into arrangements with, or acquired, biotechnology companies
          to enhance their capabilities or

     o    extensive experience in preclinical testing and human clinical trials.

     These factors may enable others to develop products and processes
competitive with or superior to our own or those of our collaborators. In
addition, a significant amount of research in biotechnology is being carried out
in universities and other non-profit research organizations. These entities are
becoming increasingly inter-



                                      -10-


ested in the commercial value of their work and may become more aggressive in
seeking patent protection and licensing arrangements.

     Furthermore, positive or negative developments in connection with a
potentially competing product may have an adverse impact on our ability to raise
additional funding on acceptable terms. For example, if another product is
perceived to have a competitive advantage, or another product's failure is
perceived to increase the likelihood that our product will fail, then investors
may choose not to invest in us on terms we would accept or at all.

     Without limiting the foregoing, we are aware that:

     o    it has been announced that Amgen Inc. tested its rheumatoid arthritis
          and psoriatic arthritis drug, Enbrel(R), in a Phase III clinical trial
          in patients with moderate-to-severe plaque psoriasis, meeting the
          primary endpoint and all secondary endpoints, that the primary and key
          secondary endpoints were met in a second Phase III trial, and that a
          filing for regulatory approval with the FDA for this medication was
          submitted in July of 2003;

     o    Biogen Inc. has announced that the FDA has approved Amevive(R) to
          treat moderate-to-severe chronic plaque psoriasis in adult patients
          who are candidates for systemic therapy or phototherapy and the
          product has been launched in the U.S.;

     o    Centocor Inc., a unit of Johnson & Johnson, has announced that it has
          tested its rheumatoid arthritis and Crohn's disease drug, Remicade(R),
          in psoriasis showing clinical benefits (and it has been announced that
          the drug has shown promising results in patients with psoriatic
          arthritis);

     o    Abbott Laboratories has announced the commencement of a Phase II
          psoriasis trial and Phase III psoriatic arthritis trial of its
          rheumatoid arthritis drug HumiraTM;

     o    MedImmune, Inc. has completed enrollment in three Phase II trials to
          evaluate its anti-T cell monoclonal antibody in psoriasis; and

     o    other companies, including Tularik Inc., are developing monoclonal
          antibody or other products for treatment of inflammatory skin
          disorders.

     A number of companies are developing monoclonal antibodies targeting
cancers, which may prove more effective than the ING-1 antibody.

     It is possible that one or more other companies may be developing one or
more products based on the same human protein as our NEUPREX(R) product, and
these product(s) may prove to be more effective than NEUPREX(R) or receive
regulatory approval prior to NEUPREX(R) or any BPI-derived product developed by
XOMA.

Even If We Or Our Third Party Collaborators Bring Products To Market, We
May Be Unable To Effectively Price Our Products Or Obtain Adequate
Reimbursement For Sales Of Our Products, Which Would Prevent Our Products
From Becoming Profitable.

     If we or our third party collaborators succeed in bringing our product
candidates to the market, they may not be considered cost-effective, and
reimbursement to the patient may not be available or may not be sufficient to
allow us to sell our products on a competitive basis. In both the United States
and elsewhere, sales of medical products and treatments are dependent, in part,
on the availability of reimbursement to the patient from third-party payors,
such as government and private insurance plans. Third-party payors are
increasingly challenging the prices charged for pharmaceutical products and
services. Our business is affected by the efforts of



                                      -11-


government and third-party payors to contain or reduce the cost of health care
through various means. In the United States, there have been and will continue
to be a number of federal and state proposals to implement government controls
on pricing. In addition, the emphasis on managed care in the United States has
increased and will continue to increase the pressure on the pricing of
pharmaceutical products. We cannot predict whether any legislative or regulatory
proposals will be adopted or the effect these proposals or managed care efforts
may have on our business.

If Our And Our Partners' Patent Protection For Our Principal Products And
Processes Is Not Enforceable, We May Not Realize Our Profit Potential.

     Because of the length of time and the expense associated with bringing new
products to the marketplace, we and our partners hold and are in the process of
applying for a number of patents in the United States and abroad to protect our
products and important processes and also have obtained or have the right to
obtain exclusive licenses to certain patents and applications filed by others.
However, the patent position of biotechnology companies generally is highly
uncertain and involves complex legal and factual questions, and no consistent
policy regarding the breadth of allowed claims has emerged from the actions of
the U.S. Patent and Trademark Office with respect to biotechnology patents.
Legal considerations surrounding the validity of biotechnology patents continue
to be in transition, and historical legal standards surrounding questions of
validity may not continue to be applied, and current defenses as to issued
biotechnology patents may not in fact be considered substantial in the future.
These factors have contributed to uncertainty as to:

     o    the degree and range of protection any patents will afford against
          competitors with similar technologies

     o    if and when patents will issue

     o    whether or not others will obtain patents claiming aspects similar to
          those covered by our patent applications or

     o    the extent to which we will be successful in avoiding infringement of
          any patents granted to others.

     The Patent Office has issued approximately 71 patents to us related to our
products based on human bactericidal permeability-increasing protein, which we
call BPI, including novel compositions, their manufacture, formulation, assay
and use. In addition, we are the exclusive licensee of BPI-related patents and
applications owned by New York University and Incyte Pharmaceuticals Inc. The
Patent Office has also issued nine patents to us related to our bacterial
expression technology.

     If certain patents issued to others are upheld or if certain patent
applications filed by others issue and are upheld, we may require licenses from
others in order to develop and commercialize certain potential products
incorporating our technology or we may become involved in litigation to
determine the proprietary rights of others. These licenses, if required, may not
be available on acceptable terms, and any such litigation may be costly and may
have other adverse effects on our business, such as inhibiting our ability to
compete in the marketplace and absorbing significant management time.

     Due to the uncertainties regarding biotechnology patents, we also have
relied and will continue to rely upon trade secrets, know-how and continuing
technological advancement to develop and maintain our competitive position. All
of our employees have signed confidentiality agreements under which they have
agreed not to use or disclose any of our proprietary information. Research and
development contracts and relationships between us and our scientific
consultants and potential customers provide access to aspects of our know-how
that are protected generally under confidentiality agreements. These
confidentiality agreements may not be honored or may not be enforced by a court.
To the extent proprietary information is divulged to competitors or to the


                                      -12-


public generally, such disclosure may adversely affect our ability to develop or
commercialize our products by giving others a competitive advantage or by
undermining our patent position.

Protecting Our Intellectual Property Can Be Costly And Expose Us To Risks Of
Counterclaims Against Us.

     We may be required to engage in litigation or other proceedings to protect
our intellectual property. The cost to us of this litigation, even if resolved
in our favor, could be substantial. Such litigation could also divert
management's attention and resources. In addition, if this litigation is
resolved against us, our patents may be declared invalid, and we could be held
liable for significant damages. In addition, if the litigation included a claim
of infringement by us of another party's patent that was resolved against us, we
or our collaborators may be enjoined from developing, manufacturing, selling or
importing products, processes or services without a license from the other
party.

The Financial Terms Of Some Of Our Existing Or Future Collaborative
Arrangements Could Result In Dilution Of Our Share Value.

     In November of 2003, we announced that we exercised our option to defer
payment of $40 million of our convertible loan from Genentech related to the
development of RAPTIVA(TM) and pay the remaining balance of approximately $29.6
million under the development loan with preference shares before year-end 2003.
These preference shares were issued in December of 2003 and are convertible into
an aggregate of 3,818,395 common shares at a conversion price of approximately
$7.75 per share, the price determined under the loan agreements at the time we
notified Genentech of our election.

     Our financing arrangement with Millennium includes a $5.0 million
convertible note we issued to Millennium in November of 2001, which comes due in
February of 2004 and may be converted into common shares at that time. In
addition, we have the option to issue up to $14.7 million worth of common
shares, excluding the convertible debt, to Millennium through February of 2005.
As of December 31, 2003, the total amount issuable in 2004 was approximately
$16.4 million. The number of shares to be issued will be based on a conversion
price to be calculated at the time of conversion. This arrangement, as well as
future arrangements we may enter into with similar effect, could result in
dilution in the value of our shares.

Because Many Of The Companies We Do Business With Are Also In The Biotechnology
Sector, The Volatility Of That Sector Can Affect Us Indirectly As Well As
Directly.

     The same factors that affect us directly because we are a biotechnology
company can also adversely impact us indirectly by affecting the ability of our
collaborators, partners and others we do business with to meet their obligations
to us or our ability to realize the value of the consideration provided to us by
these other companies. For example, in connection with our licensing
transactions relating to our bacterial expression technology, we have in the
past and may in the future agree to accept equity securities of the licensee in
payment of license fees. The future value of these or any other shares we
receive is subject both to market risks affecting our ability to realize the
value of these shares and more generally to the business and other risks to
which the issuer of these shares may be subject.

As We Do More Business Internationally, We Will Be Subject To Additional
Political, Economic And Regulatory Uncertainties.

     We may not be able to successfully operate in any foreign market. We
believe that, because the pharmaceutical industry is global in nature,
international activities will be a significant part of our future business
activities and that, when and if we are able to generate income, a substantial
portion of that income will be derived from product sales and other activities
outside the United States. Foreign regulatory agencies often establish standards
different from those in the United States, and an inability to obtain foreign
regulatory approvals on



                                      -13-


a timely basis could put us at a competitive disadvantage or make it
uneconomical to proceed with a product's development. International operations
may be limited or disrupted by:

     o    imposition of government controls,

     o    export license requirements,

     o    political or economic instability,

     o    trade restrictions,

     o    changes in tariffs,

     o    restrictions on repatriating profits,

     o    exchange rate fluctuations,

     o    withholding and other taxation, and

     o    difficulties in staffing and managing international operations.

Because We Are A Relatively Small Biopharmaceutical Company With
Limited Resources, We May Not Be Able To Attract And Retain
Qualified Personnel, And The Loss Of Key Personnel Could Delay Or
Prevent Achieving Our Objectives.

     Our success in developing marketable products and achieving a competitive
position will depend, in part, on our ability to attract and retain qualified
scientific and management personnel, particularly in areas requiring specific
technical, scientific or medical expertise. There is intense competition for
such personnel. Our research, product development and business efforts would be
adversely affected by the loss of one or more of key members of our scientific
or management staff, particularly our executive officers: John L. Castello, our
Chairman of the Board, President and Chief Executive Officer; Patrick J.
Scannon, M.D., Ph.D., our Senior Vice President and Chief Scientific and Medical
Officer; Clarence L. Dellio, our Senior Vice President and Chief Operating
Officer; Peter B. Davis, our Vice President, Finance and Chief Financial
Officer; and Christopher J. Margolin, our Vice President, General Counsel and
Secretary. We have employment agreements with Mr. Castello, Dr. Scannon and Mr.
Davis. We currently have no key person insurance on any of our employees.

We Are Exposed To An Increased Risk Of Product Liability Claims.

     The sale, testing and marketing of medical products entails an inherent
risk of allegations of product liability. We believe that we currently have
adequate levels of insurance for our clinical trials, however, in the event of
one or more large, unforeseen awards, such levels may not provide adequate
coverage. We will seek to obtain additional insurance, if needed, as
commercialization of RAPTIVA(TM) continues; however, because we have not yet
determined whether additional insurance is needed, we do not know whether
adequate insurance coverage will be available or be available at acceptable
costs. A significant product liability claim for which we were not covered by
insurance would have to be paid from cash or other assets. To the extent we have
sufficient insurance coverage, such a claim would result in higher subsequent
insurance rates.

We May Be Subject To Increased Risks Because We Are A Bermuda Company.

     Alleged abuses by certain companies that have changed their legal domicile
from jurisdictions within the United States to Bermuda have created an
environment where, notwithstanding that we changed our legal domicile in a
transaction that was approved by our shareholders and fully taxable to our
company under U.S. law, we may be exposed to various prejudicial actions,
including:



                                      -14-


     o    "blacklisting" of our common shares by certain pension funds;

     o    legislation restricting certain types of transactions; and

     o    punitive tax legislation.

     We do not know whether any of these things will happen, but if implemented
one or more of them may have an adverse impact on our future operations or our
share price.

If You Were To Obtain A Judgment Against Us, It May Be Difficult To Enforce
Against Us Because We Are A Foreign Entity.

     We are a Bermuda company. All or a substantial portion of our assets may be
located outside the United States. As a result, it may be difficult for
shareholders and others to enforce in United States courts judgments obtained
against us. We have irrevocably agreed that we may be served with process with
respect to actions based on offers and sales of securities made hereby in the
United States by serving Christopher J. Margolin, c/o XOMA Ltd., 2910 Seventh
Street, Berkeley, California 94710, our United States agent appointed for that
purpose. We have been advised by our Bermuda counsel, Conyers Dill & Pearman,
that there is doubt as to whether Bermuda courts would enforce judgments of
United States courts obtained in actions against XOMA or our directors and
officers that are predicated upon the civil liability provisions of the U.S.
securities laws or certain original actions brought in Bermuda against XOMA or
such persons predicated upon the U.S. securities laws. There is no treaty in
effect between the United States and Bermuda providing for such enforcement, and
there are grounds upon which Bermuda courts may not enforce judgments of United
States courts. Certain remedies available under the United States federal
securities laws may not be allowed in Bermuda courts as contrary to that
nation's policy.

Our Shareholder Rights Agreement Or Bye-laws May Prevent Transactions That
Could Be Beneficial To Our Shareholders And May Insulate Our Management From
Removal.

     In February of 2003, we adopted a new shareholder rights agreement (to
replace the shareholder rights agreement that had expired), which could make it
considerably more difficult or costly for a person or group to acquire control
of XOMA in a transaction that our board of directors opposes.

     Our bye-laws:

     o    require certain procedures to be followed and time periods to be met
          for any shareholder to propose matters to be considered at annual
          meetings of shareholders, including nominating directors for election
          at those meetings;

     o    authorize our board of directors to issue up to 1,000,000 preference
          shares without shareholder approval and to set the rights, preferences
          and other designations, including voting rights, of those shares as
          the board of directors may determine; and

     o    contain provisions, similar to those contained in the Delaware General
          Corporation Law, that may make business combinations with interested
          shareholders more difficult.

     These provisions of our shareholders rights agreement and our bye-laws,
alone or in combination with each other, may discourage transactions involving
actual or potential changes of control, including transactions that otherwise
could involve payment of a premium over prevailing market prices to holders of
common shares, could limit the ability of shareholders to approve transactions
that they may deem to be in their best interests, and could make it considerably
more difficult for a potential acquiror to replace management.



                                      -15-


Risks Relating To This Offering

The Actual Or Anticipated Resale By Genentech Of Our Common Shares
That We Issue To Genentech Upon Conversion Of The Preference Shares
Or Which Genentech Otherwise Owns Or Acquires May Have An Adverse
Impact On The Market Price Of Our Common Shares

     The resale by Genentech through open market transactions or other means of
the common shares that we issue to Genentech upon conversion of the preference
shares we have issued to them or that it otherwise owns or acquires may,
depending upon the timing of the resales, depress the market price of our common
shares. Moreover, as all the common shares issue upon conversion will be
available for immediate resale, the mere prospect of our sales to it could
depress the market price of our common shares. In addition, actual or
anticipated downward pressure on the market price of our common shares due to
actual or anticipated resales of our common shares by Genentech could cause some
institutions or individuals to engage in short sales of our common shares, which
may itself cause the market price of our common shares to decline.

Our Issuance Of Common Shares To Genentech Will Reduce The
Percentage Equity Ownership Of Our Existing Shareholders

     We may issue to Genentech up to 3,818,395 of our common shares upon
conversion of the preference shares. This issuance of common shares to Genentech
will proportionately decrease our existing shareholders' percentage ownership of
our total outstanding equity interests.




                                      -16-




         INCORPORATION OF INFORMATION WE FILE WITH THE SEC

     The following documents filed by XOMA with the SEC pursuant to the
Securities Exchange Act are "incorporated by reference" in this prospectus,
which means we can disclose important information to you by referring you to
these documents and they are considered to be a part of this prospectus:

          (1) annual report on Form 10-K for the fiscal year ended December 31,
     2002 (file no. 0-14710);

          (2) quarterly reports on Form 10-Q for the quarterly periods ended
     March 31, 2003, June 30, 2003 and September 30, 2003, respectively (file
     no. 0-14710);

          (3) current report on Form 8-K dated and filed on November 27, 2001,
     as amended by amendments on Form 8-K/A dated and filed on December 13,
     2001, October 24, 2002 and May 21, 2003, respectively (file no. 0-14710);

          (4) current report on Form 8-K dated and filed on April 11, 2003, as
     amended by amendment on Form 8-K/A filed on April 18, 2003 (file no.
     0-14710);

          (5) current report on Form 8-K dated and filed on June 30, 2003 (file
     no. 0-14710);

          (6) current report on Form 8-K dated September 9, 2003 and filed on
     September 10, 2003 (file no. 0-14710);

          (7) current report on Form 8-K dated September 19, 2003 and filed on
     September 24, 2003 (file no. 0-14710);

          (8) current report on Form 8-K dated and filed on October 10, 2003
     (file no. 0-14710);

          (9) current report on Form 8-K dated and filed on December 18, 2003,
     as amended by amendment on Form 8-K/A filed on January 9, 2004 (file no.
     0-14710);

          (10) current report on Form 8-K dated and filed on January 6, 2004
     (file no. 0-14710); and

          (11) the description of the common shares in the registration
     statement on Form 8-A dated and filed on April 1, 2003 under Section 12 of
     the Securities Exchange Act, including any amendment or report for the
     purpose of updating such description (file no. 0-14710).

     All documents filed by XOMA with the SEC pursuant to Section 13(a), 13(c),
14 or 15(d) of the Securities Exchange Act after the date of this prospectus and
before all of the common shares offered by this prospectus have been sold are
deemed to be incorporated by reference in, and to be part of, this prospectus
from the date any such document is filed.

     Any statements contained in a document incorporated by reference in this
prospectus are deemed to be modified or superseded for purposes of this
prospectus to the extent that a statement contained in this prospectus (or in
any other subsequently filed document which also is incorporated by reference in
this prospectus) modifies or supersedes such statement. Any statement so
modified or superseded is not deemed to constitute a part of this prospectus
except as so modified or superseded.




                                      -17-




                SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

     Some of the statements made in this prospectus are forward-looking in
nature, including those relating to the sufficiency of our cash resources and
the marketing and sales effort for RAPTIVA(TM), as well as other statements
related to current plans for product development and existing and potential
collaborative and licensing relationships, or that otherwise relate to future
periods and other statements that are not historical facts. The words "believe,"
"plan," "intend," "expect" and similar expressions are intended to identify
forward-looking statements. We caution you not to place undue reliance on these
forward-looking statements. They apply only as of the date of this prospectus
except that statements incorporated by reference from previously filed reports
apply as of the date made. The occurrence of the events described, and the
achievement of the intended results, depend on many events, some or all of which
are not predictable or not within our control. Actual results may differ
materially from those anticipated in any forward-looking statements. Many risks
and uncertainties are inherent in the biopharmaceutical industry. Others are
more specific to our business. Many of the significant risks related to our
business are described in this prospectus. These include, among others, the
period for which our cash resources are sufficient could be shortened if
expenditures are made earlier or in larger amounts than anticipated or are
unanticipated or if funds are not available on acceptable terms; and the
marketing and sales effort for RAPTIVA(TM) may not be successful due to the
strength of competition or if physicians do not adopt the product as treatment
for their patients. These and other risks, including those related to the
results of pre-clinical testing; the timing or results of pending and future
clinical trials (including the design and progress of clinical trials; safety
and efficacy of the products being tested; action, inaction or delay by the FDA,
European or other regulators or their advisory bodies; and analysis or
interpretation by, or submission to, these entities or others of scientific
data); changes in the status of existing collaborative relationships; the
ability of collaborators and other partners to meet their obligations;
competition; market demand for products; scale-up and marketing capabilities;
availability of additional licensing or collaboration opportunities;
international operations; share price volatility; our financing needs and
opportunities; uncertainties regarding the status of biotechnology patents;
uncertainties as to the costs of protecting intellectual property; and risks
associated with our status as a Bermuda company are described in more detail in
"Risk Factors." We undertake no obligation to publicly update any
forward-looking statements, regardless of any new information, future events or
other occurrences. We advise you, however, to consult any additional disclosures
we make in our reports to the SEC on Forms 10-K, 10-Q and 8-K.

                              ____________________

     We have not authorized any dealer, salesperson or other person to give you
written information other than this prospectus or to make representations as to
matters not stated in this prospectus. You must not rely on unauthorized
information. This prospectus is not an offer to sell these common shares or our
solicitation of your offer to buy the common shares in any jurisdiction where
that would not be permitted or legal. Neither the delivery of this prospectus
nor any sales made hereunder after the date of this prospectus should imply that
the information contained in this prospectus or the affairs of XOMA have not
changed since the date of this prospectus.




                                      -18-




              PRICE RANGE OF COMMON SHARES AND DIVIDEND INFORMATION

     XOMA's common shares (such common shares and the common stock of our
predecessor Delaware corporation are referred to in this prospectus as the
common shares) trade on the Nasdaq National Market under the symbol "XOMA." The
following table sets forth the quarterly range of high and low reported sale
prices of the common shares on the Nasdaq National Market for the periods
indicated (in United States dollars):

                                                            High         Low
                                                            ----         ---

   2002:

                First Quarter                            $12.190        $7.510
                Second Quarter                             8.510         3.000
                Third Quarter                              7.200         3.250
                Fourth Quarter                             6.250         3.800

   2003:

                First Quarter                             $4.600        $2.840
                Second Quarter                            $8.000        $3.790
                Third Quarter                            $10.700        $5.040
                Fourth Quarter                            $8.250        $5.850

   2004:

                First Quarter (through January 20)        $7.710        $6.600

     On January 20, 2004 the last reported sale price of the common shares as
reported on the Nasdaq National Market was $7.18 per share. As of January 20,
2004, there were approximately 3,039 record holders of XOMA's common shares.

     XOMA has not paid dividends on its common equity. XOMA currently does not
intend to pay dividends and intends to retain any earnings for use in its
business and the financing of its capital requirements for the foreseeable
future. The payment of any future cash dividends on XOMA's common shares will
necessarily be dependent upon the earnings and financial needs of XOMA, along
with applicable legal and contractual restrictions.




                                      -19-




                                 USE OF PROCEEDS

     We will not receive any proceeds from the sale of the common shares by the
selling shareholder to you.

     We have used the proceeds from the common shares previously issued to
Genentech covered by this prospectus and the convertible subordinated debt
issued to Genentech, which was repaid in part with the issuance of preference
shares that are convertible into common shares covered by this prospectus, for
the development of RAPTIVA(TM), a humanized anti-CD11a monoclonal antibody, in
collaboration with Genentech.




                                      -20-




                               SELLING SHAREHOLDER

     The selling shareholder is Genentech, Inc. As part of our financing
arrangement with Genentech, we issued 2,959 Series B Preference Shares
representing repayment of $29,590,000 of a development loan made by Genentech to
us. Each Preference Share is convertible into that number of our common shares
equal to $10,000 divided by the conversion price of approximately $7.75. Upon
conversion of the preference shares, Genentech will receive 3,818,395 of our
common shares.

     The following table sets forth certain information regarding the ownership
of common shares by the selling shareholder as of January 20, 2004, and the
number of common shares covered by this prospectus:



                                                                                                 Ownership
                                            Ownership                                         of common shares
                                         of common shares                             after the offering (assuming all
                                      prior to the offering                             shares offered are sold)(1)
                                      ---------------------                           --------------------------------
                                                                     Number
              Name of                         Number               of Shares           Number of            Percent
        Selling Shareholder                 of Shares               Offered             Shares              of Class
---------------------------------         -------------          ------------         -----------           ---------
                                                                                                  
Genentech, Inc. (2)                       3,868,395(3)           3,868,395(3)               0                 0%




(1)  For the purposes of this filing, we have assumed that all of the shares
     included in this registration statement will be sold; however, there is no
     contractual or other arrangement requiring any of the shares to be sold.

(2)  The management of Genentech has voting and investment control over the
     common shares.

(3)  Represents (i) 50,000 common shares held by Genentech and (ii) 3,818,395 of
     our common shares into which the preference shares issued to Genentech may
     be converted based on the conversion price of approximately $7.75 per
     share.

     As of January 20, 2004, the selling shareholder holds 50,000 of our common
shares. The selling shareholder is deemed to be beneficial owners of 3,818,395
common shares issuable upon the conversion of the preference shares. Assuming
the selling shareholder sells all of the common shares that it has acquired
pursuant to its arrangement with us and does not otherwise acquire our common
shares, it will not own any of our common shares after its sale of the common
shares to you.

Material Terms Of Arrangement With Genentech

     In April of 1996, we entered into a collaborative agreement with Genentech
to jointly develop RAPTIVA(TM) for treatment of psoriasis and organ transplant
rejection. In connection with the agreement, Genentech purchased 1.5 million
common shares for approximately $9.0 million and agreed to lend us our share of
the development costs for RAPTIVA(TM) until the completion of Phase III clinical
trials and FDA approval. This funding was through the issuance of convertible
subordinated notes due at the earlier of April of 2005 or upon regulatory
approval of RAPTIVA(TM).

     On October 27, 2003, the FDA approved RAPTIVA(TM) for the treatment of
chronic moderate-to-severe plaque psoriasis in adults who are candidates for
systemic therapy or phototherapy. Under the terms of our financing arrangement
with Genentech, this approval triggered a 90-day period at the end of which the
convertible subordinated debt would have matured. For payment of the convertible
subordinated debt, we elected pursuant to the development loan agreement to
defer payment of $40.0 million as an offset against our proceeds from our



                                      -21-


25% share of U.S. operating profits on the product and to pay the remaining
balance (approximately $29.6 million) with preference shares before December 31,
2003. These preference shares were issued in December of 2003 and are
convertible into an aggregate of 3,818,395 common shares at a conversion price
of approximately $7.75 per share.

     We have agreed to register the resale of the common shares that we may
issue to Genentech upon conversion of these preference shares. This prospectus
is intended to satisfy these registration obligations.

     The 3,868,395 shares covered by this prospectus consist of

     o    50,000 common shares held by Genentech; and

     o    3,818,395 of our common shares into which the preference shares issued
          to Genentech may be converted based on the conversion price of
          approximately $7.75 per share

and in the aggregate would have represented approximately 4.6% of our
outstanding common shares as of January 20, 2004, after giving effect to their
issuance.




                                      -22-




                          DESCRIPTION OF SHARE CAPITAL

     The following statements with respect to our share capital are subject to
the detailed provisions of our memorandum of continuance and bye-laws. These
statements do not purport to be complete and, while we believe the descriptions
of the material provisions of the memorandum of continuance and bye-laws
incorporated by reference are accurate statements with respect to such material
provisions, such statements are subject to the detailed provisions in the
memorandum of continuance and bye-laws, to which reference is hereby made for a
full description of such provisions.

COMMON SHARES

General

     The memorandum of continuance and the bye-laws provide that our authorized
common share capital is limited to 135,000,000 common shares, par value
U.S.$.0005 per share. As of January 20, 2004, there were 84,097,666 common
shares outstanding.

Voting

     The holders of common shares are entitled to one vote per share. All
actions submitted to a vote of shareholders shall be voted on by the holders of
common shares, voting together as a single class (together with the Series A
preference shares (as described below), if any), except as provided by law.

Dividends

     Holders of common shares are entitled to participate, on a share for share
basis, with the holders of any other common shares outstanding, with respect to
any dividends declared by our board of directors, subject to the rights of
holders of preference shares. Dividends will generally be payable in U.S.
dollars. We have not paid cash dividends on the common shares. We currently do
not intend to pay dividends and intend to retain any of our earnings for use in
our business and the financing of our capital requirements for the foreseeable
future. The payment of any future cash dividends on the common shares is
necessarily dependent upon our earnings and financial needs, along with
applicable legal and contractual restrictions.

Liquidation

     On a liquidation of XOMA, holders of common shares will be entitled to
receive any assets remaining after the payment of our debts and the expenses of
the liquidation, subject to such special rights as may be attached to any other
class of shares.

Redemption

     The common shares are not subject to redemption either by us or the holders
thereof.

Variation of Rights

     Under our bye-laws, if at any time our share capital is divided into
different classes of shares, the rights attached to any class (unless otherwise
provided by the terms of the issue of the shares of that class) may be varied
with the consent in writing of the holders of a majority of the issued shares of
that class or with the sanction of a resolution passed by the holders of a
majority of such shares at a separate general meeting.



                                      -23-


PREFERENCE SHARES

General

     Under our memorandum of continuance and bye-laws, we have the authority to
issue 1,000,000 preference shares, par value U.S.$.05 per share. Of these,
135,000 preference shares have been designated Series A Preference Shares and
8,000 preference shares have been designated Series B Preference Shares. Under
our bye-laws, subject to the special rights attaching to any class of our shares
not being varied and to any resolution approved by the holders of 75% of the
issued shares entitled to vote in respect thereof, our board of directors may
establish one or more classes or series of preference shares having the number
of shares, designations, relative voting rights, dividend rates, liquidation and
other rights, preferences and limitations that the board of directors fixes
without any shareholder approval.

The Series A Preference Shares

     There are no Series A preference shares outstanding. Pursuant to the rights
of the Series A preference shares, subject to the rights of holders of any
shares of any series of preference shares ranking prior and superior, the
holders of Series A preference shares are entitled to receive, when, as and if
declared by our board of directors out of funds legally available for the
purpose, quarterly dividends payable in cash on the first day of March, June,
September and December in each year, commencing on the first dividend payment
date after the first issuance of a share or fraction of a share of Series A
preference shares, in an amount per share equal to the greater of (a) U.S.$1.00
or (b) 1,000 times the aggregate per share amount of all cash dividends, plus
1,000 times the aggregate per share amount of all non-cash dividends or other
distributions, other than a dividend or bonus issue payable in common shares,
declared on the common shares since the immediately preceding dividend payment
date, or, with respect to the first dividend payment date, since the first
issuance of Series A preference shares.

     In addition to any other voting rights required by law, holders of Series A
preference shares shall have the right to vote on all matters submitted to a
vote of our shareholders with each share of Series A preference shares entitled
to 1,000 votes. Except as otherwise provided by law, holders of Series A
preference shares, holders of common shares and holders of any other shares
having general voting rights shall vote together as one class on all matters
submitted to a vote of our shareholders.

     Unless otherwise provided in the rights attaching to a subsequently
designated series of our preference shares, the Series A preference shares shall
rank junior to any other series of preference shares subsequently issued as to
the payment of dividends and distribution of assets on liquidation, dissolution
or winding-up and shall rank senior to the common shares. Upon any liquidation,
dissolution or winding-up of XOMA, no distributions shall be made to holders of
shares ranking junior to the Series A preference shares unless, prior thereto,
the holders of Series A preference shares shall have received an amount equal to
accrued and unpaid dividends and distributions, whether or not declared, to the
date of such payment, plus an amount equal to the greater of (1) U.S.$100.00 per
share or (2) an aggregate amount per share equal to 1,000 times the aggregate
amount to be distributed per share to holders of common shares or to the holders
of shares ranking on parity with the Series A preference shares, except
distributions made ratably on the Series A preference shares and all other such
parity shares in proportion to the total amount to which the holders of all such
shares are entitled upon such liquidation, dissolution or winding-up.

     If we shall enter into any consolidation, amalgamation, merger, combination
or other transaction in which common shares are exchanged for or changed into
cash, other securities and/or any other property, then any Series A preference
shares outstanding shall at the same time be similarly exchanged or changed in
an amount per share equal to 1,000 times the aggregate amount of cash,
securities and/or other property, as the case may be, into which or for which
each common share is changed or exchanged.

     The Series A preference shares shall not be redeemable.



                                      -24-


The Series B Preference Shares

     8,000 Series B preference shares have been designated for issuance of which
2,959 Series B preference shares were issued upon conversion of the convertible
subordinated loans to us made by Genentech in connection with the funding of the
our development costs for RAPTIVA(TM) following the regulatory approval of
RAPTIVA(TM). Pursuant to the rights of the Series B preference shares, the
holders of Series B preference shares will not be entitled to receive any
dividends on the Series B preference shares.

     The Series B preference shares will rank senior with respect to rights on
liquidation, winding-up and dissolution of XOMA to all classes of common shares.
Upon any voluntary or involuntary liquidation, dissolution or winding-up of
XOMA, holders of Series B preference shares will be entitled to receive
U.S.$10,000 per share of Series B preference shares before any distribution is
made on the common shares. The holders of Series B preference shares will have
no voting rights, except as required under Bermuda law.

     The holders of Series B preference shares will have the right to convert
Series B preference shares into common shares at a conversion price equal to the
current market price of the common shares (determined as provided below). The
current market price will be determined (a) for Series B preference shares
issued in connection with a conversion of one or more of the convertible
subordinated loans upon certain regulatory approvals, payment defaults or in
certain other circumstances, as of the date on which XOMA gives notice of its
intention to convert, and (b) for Series B preference shares issued in
connection with certain prepayments of one or more of the convertible
subordinated loans or a conversion thereof in certain other circumstances, as of
the date XOMA gives notice of its intention to prepay.

     The Series B preference shares will be automatically converted into common
shares at its then effective conversion rate immediately upon the transfer by
the initial holder to any third party which is not an affiliate of such holder.

     We will have the right, at any time and from time to time, to redeem any or
all Series B preference shares for cash in an amount equal to the conversion
price multiplied by the number of common shares into which each such share of
Series B preference shares would then be convertible.

OUTSTANDING WARRANTS

     XOMA issued 250,000 common stock purchase warrants to Incyte in July of
1998, of which 125,000 remain outstanding. Each Incyte warrant outstanding
entitles the holder thereof to purchase one common share, subject to
anti-dilution adjustments. A holder may exercise the Incyte warrants at an
exercise price of $6.00 per share on or before July 9, 2008 or earlier upon the
related license becoming fully paid up. Incyte is the holder of these warrants
and received them as part of the consideration for the grant to XOMA of an
exclusive license to all of Incyte's patent rights relating to BPI.

     XOMA issued 379,000 warrants to purchase common shares in January of 1999
and March of 1999, of which 75,000 remain outstanding. Each January and March
1999 warrant entitles the holder thereof to purchase one common share, subject
to anti-dilution adjustments. The current holder, Otape Investments LLC, may
exercise the January and March 1999 warrants at an exercise price of $5.85 per
share on or before January 29, 2004.

     XOMA issued 150,000 warrants to purchase common shares in July of 1999.
Each July 1999 warrant entitles the holder thereof to purchase one common share,
subject to anti-dilution adjustments. A holder may exercise the July 1999
warrants at an exercise price of $5.75 per share on or before July 21, 2004.
Sutro & Co. Incorporated and Arnhold and S. Bleichroeder, Inc. are the holders
of these warrants and received them as consideration for their services as
placement agents for a private placement of our common shares in July of 1999.

     XOMA issued 250,000 warrants to purchase common shares in February of 2000.
Each February 2000 warrant entitles the holder thereof to purchase one common
share, subject to anti-dilution adjustments. A holder



                                      -25-


may exercise the February 2000 warrants at an exercise price of $5.00 per share
on or before February 11, 2005. Sutro & Co. Incorporated and Arnhold and S.
Bleichroeder, Inc. are the holders of these warrants and received them as
consideration for their services as placement agents for a private placement of
our common shares in February of 2000.

     All of the warrants described above were issued in reliance on the
exemption from registration provided in Section 4(2) of the Securities Act. None
of the warrants described above have been registered under the Securities Act
and none may be transferred except pursuant to an effective registration
statement under the Securities Act or pursuant to an exception from registration
thereunder. Additionally, all of the warrants contain certain restrictions on
their transfer. XOMA is not obligated and does not intend to register the
warrants under the Securities Act.

                              PLAN OF DISTRIBUTION

     Any or all of the common shares being offered by this prospectus may be
sold from time to time to purchasers directly by the selling shareholder or by
pledgees, donees, transferees or other successors in interest. Alternatively,
the selling shareholder may from time to time offer any or all of the common
shares through underwriters, brokers, dealers or agents who may receive
compensation in the form of underwriting discounts, concessions or commissions
from the selling shareholder and/or the purchasers of common shares for whom
they may act. The selling shareholder, and any such underwriters, brokers,
dealers or agents that participate in the distribution of common shares, are
underwriters, and any profit on the sale of the common shares by them and any
discounts, commissions or concessions received by them may be deemed to be
underwriting discounts and commissions under the Securities Act. Any such common
shares may be so offered or sold in the open market, on the Nasdaq National
Market or such other exchange or market where our common shares are then traded,
in privately negotiated transactions (subject to limitations imposed by the
investment agreement), in an underwritten offering, in block trades, to a broker
or dealer for its account in ordinary brokerage transactions, or a combination
of such methods. The selling shareholder will make such sales at market prices
prevailing at the time of sale, at prices related to such prevailing market
prices or at negotiated prices. To the extent required, the name of the selling
shareholder, the number of common shares to be sold, the purchase price, the
public offering price, the name of any agent, dealer, broker or underwriter and
any applicable commission or discount or other items constituting compensation
or indemnification arrangements with respect to a particular offering will be
set forth in an accompanying prospectus supplement. These and other matters may
also be addressed in one or more post-effective amendments to the registration
statement of which this prospectus is a part. XOMA will receive no proceeds from
the sale by the selling shareholder of the common shares offered by this
prospectus.

     In connection with distributions of the common shares, and subject to
limitations imposed by the investment agreement, the selling shareholder may
enter into option, equity forward, collar or other transactions with
broker-dealers that involve the delivery of the common shares to the
broker-dealers, which may then resell or otherwise transfer such common shares.
The selling shareholder also may loan or pledge the common shares to a
broker-dealer and the broker-dealer may sell the common shares so loaned or upon
a default may sell or otherwise transfer the pledged common shares.

     In addition, the selling shareholder and any other persons participating in
the sale or distribution of the shares offered by this prospectus will be
subject to liability under the federal securities laws and must comply with the
requirements of the Securities Act and the Securities Exchange Act, including
Rule 10b-5 and Regulation M under the Securities Exchange Act. These rules and
regulations may limit the timing of purchases and sales of our common shares by
the selling shareholder or such other persons. Under these rules and
regulations, the selling shareholder and such other persons:

o    may not engage in any stabilization activity in connection with our common
     shares;

o    must furnish each broker which offers our common shares covered by this
     prospectus with the number of copies of this prospectus and any prospectus
     supplement which are required by such broker; and



                                      -26-


o    may not bid for or purchase any of our common shares or attempt to induce
     any person to purchase any of our common shares other than as permitted
     under the Securities Exchange Act.

     These restrictions may affect the marketability of our common shares by the
selling shareholder.

     To permit the selling shareholders to resell our common shares issued to it
upon conversion of the preferred shares, we agreed to register those shares and
to maintain that registration. We have also agreed with the selling shareholder
that, subject to limited exceptions for specified time periods, we will prepare
and file any amendments and supplements to this prospectus and the registration
statement of which it is a part as may be necessary to keep the registration
statement current and effective until:

o    the date on which the selling shareholder may sell all of the common shares
     then held by the selling shareholder issued to it upon conversion of the
     preferred shares without restriction by the volume limitations of Rule
     144(e) of the Securities Act; or

o    the date after which all of our common shares held by the selling
     shareholder that are covered by the registration statement have been sold
     by the selling shareholder under a registration statement or pursuant to
     Rule 144.

     We have agree to indemnify and hold harmless the selling shareholder, any
broker-dealer named in the registration statement of which this prospectus is a
part and their respective controlling persons against certain liabilities,
including liabilities under the Securities Act, which may be based upon, among
other things, any untrue statement or alleged untrue statement of a material
fact contained in or incorporated by reference into the registration statement
or any omission or alleged omission to state in the registration statement or
any document incorporated by reference into the registration statement a
material fact required to be stated therein or necessary to make the statements
therein not misleading, unless made or omitted in reliance upon and in
conformity with written information provided to us by the selling shareholder or
such broker-dealer.

     All expenses incurred by XOMA in complying with the registration rights
granted to the selling shareholder pursuant to which the registration statement
to which this prospectus relates has been filed, estimated to be approximately
$115,000, will be borne by XOMA. As and when XOMA is required to update this
prospectus, it may incur additional expenses in excess of this estimated amount.

     Any common shares offered by this prospectus that qualify for sale pursuant
to Rule 144 under the Securities Act may be sold under such rule rather than
pursuant to this prospectus.

                                  LEGAL OPINION

     The validity of the common shares to which this prospectus relates has been
passed upon for XOMA by Conyers Dill & Pearman, located in Hamilton, Bermuda.

                                     EXPERTS

     The consolidated financial statements of XOMA Ltd. appearing in XOMA Ltd.'s
Annual Report (Form 10-K) for the year ended December 31, 2002, have been
audited by Ernst & Young LLP, independent auditors, as set forth in their report
thereon included therein and incorporated herein by reference. Such consolidated
financial statements are incorporated herein by reference in reliance upon such
report given on the authority of such firm as experts in accounting and
auditing.

                WHERE YOU CAN GET MORE INFORMATION

     This prospectus is part of a registration statement that we have filed with
the SEC. The registration statement contains exhibits and other information not
included in this prospectus. At your request, we will pro-



                                      -27-


vide you, without charge, a copy of any documents incorporated by reference in,
or included as exhibits to, our registration statement. If you would like more
information, write or call us at:

                                    XOMA Ltd.
                               2910 Seventh Street
                               Berkeley, CA 94710
                            Telephone: (510) 204-7273

     XOMA files annual, quarterly and current reports, proxy statements and
other information with the SEC. You may read and copy any reports, statements
and other information we file at the SEC's public reference room at 450 Fifth
Street, N.W., Washington D.C. 20549. You can request copies of these documents,
upon payment of a duplicating fee, by writing to the SEC. Please call the SEC at
1-800-SEC-0330 for further information on the operation of the public reference
room. XOMA's SEC filings are also available to the public on the SEC Internet
site at http://www.sec.gov.




                                      -28-