As filed with the Securities and Exchange Commission on May 23, 2003
                                                     Registration No. 333-101035
--------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                               __________________

                         POST-EFFECTIVE AMENDMENT NO. 1
                                       TO
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933
                               __________________

                                    XOMA Ltd.
             (Exact name of registrant as specified in its charter)

             Bermuda                                        52-2154066
 (State or other jurisdiction of                         (I.R.S. Employer
  incorporation or organization)                       Identification No.)

                               2910 Seventh Street
                           Berkeley, California 94710
                                 (510) 204-7200
               (Address, including ZIP code, and telephone number,
                 including area code, of registrant's principal
                               executive offices)
                               __________________

                          CHRISTOPHER J. MARGOLIN, ESQ.
                                    XOMA Ltd.
                               2910 Seventh Street
                           Berkeley, California 94710
                                 (510) 204-7292
                     (Name, address, including ZIP code, and
                     telephone number, including area code,
                              of agent for service)
                               __________________

                                    Copy to:
                           GEOFFREY E. LIEBMANN, ESQ.
                             CAHILL GORDON & REINDEL
                                 80 Pine Street
                            New York, New York 10005
                                 (212) 701-3000
                               __________________

Approximate date of commencement of proposed sale to the public: From time to
time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant
to dividend or interest reinvestment plans, please check the following box. / /

If any of the securities being registered on this Form are to be offered on a
delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. /X/

If this Form is filed to register additional securities for an offering pursuant
to Rule 462(b) under the Securities Act, please check the following box and list
the Securities Act registration statement number of the earlier effective
registration statement for the same offering. / /

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under
the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /








Explanatory Note

     Pursuant to a Registration Statement on Form S-3 (Registration No.
333-101035) ("Registration Statement"), XOMA Ltd., a Bermuda company (the
"Registrant"), registered 5,000,000 of its common shares. The Registration
Statement was declared effective on December 13, 2002.

     The purpose of this Post-Effective Amendment to the Registration Statement
is to deregister and remove from registration the 5,000,000 common shares
previously registered on the Registration Statement. No securities have been
sold in connection with the Registration Statement. This action is caused by the
Registrant's renegotiation of certain material provisions of the agreements by
which investors have obligated themselves to purchase common shares of the
Registrant and for which the Registration Statement was filed. Contemporaneously
with the filing of this letter, the Registrant has filed a new registration
statement on Form S-3 which reflects the new terms of the agreements.



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                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Berkeley, State of California, on May 23, 2003.


                                 XOMA LTD.



                                 By:  /s/ John L. Castello
                                     ----------------------------------
                                     Name:    John L. Castello
                                     Title:   Chairman of the Board,
                                              President and Chief
                                              Executive Officer


                                      S-1



     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.





               Signature                                     Title                                 Date
               ---------                                     -----                                 ----

                                                                                         
                                         Chairman of the Board, President and Chief            May 23, 2003
                                         Executive Officer (Principal Executive
/s/ John L. Castello                     Officer)
---------------------------------
John L. Castello

                                         Chief Scientific and Medical Officer and              May 23, 2003
                    *                    Director
---------------------------------
Patrick J. Scannon

                                         Vice President, Finance and Chief Financial           May 23, 2003
                                         Officer (Principal Financial and Accounting
                    *                    Officer)
---------------------------------
Peter B. Davis

                    *                    Director                                              May 23, 2003
---------------------------------
James G. Andress

                    *                    Director                                              May 23, 2003
---------------------------------
William K. Bowes, Jr.

                    *                    Director                                              May 23, 2003
---------------------------------
Arthur Kornberg

                    *                    Director                                              May 23, 2003
---------------------------------
Steven C. Mendell

                    *                    Director                                              May 23, 2003
---------------------------------
W. Denman Van Ness

                    *                    Director                                              May 23, 2003
---------------------------------
Patrick J. Zenner


*  By: /s/  Christopher J.Margolin
       ---------------------------------
         Christopher J. Margolin,
         Attorney-in-Fact




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