Filed by Sanofi-Synthelabo
                                      Pursuant to Rule 165 and Rule 425(a) under
                            the United States Securities Act of 1933, as amended

                                                        Subject Company: Aventis
                                                   Commission File No. 001-10378
                                                             Date: June 14, 2004


         On June 14, 2004, Sanofi-Synthelabo issued the following press release.

         In connection with the proposed acquisition of Aventis,
Sanofi-Synthelabo has filed with the United States Securities and Exchange
Commission (SEC), a registration statement on Form F-4 (File no: 333-112314),
which includes a prospectus and a prospectus supplement relating to the revised
offer, and related exchange offer materials, to register the Sanofi-Synthelabo
ordinary shares (including Sanofi-Synthelabo ordinary shares represented by
Sanofi-Synthelabo ADSs) to be issued in exchange for Aventis ordinary shares
held by holders located in the United States and for Aventis ADSs held by
holders wherever located and has also filed with the SEC a Statement on Schedule
TO. INVESTORS AND HOLDERS OF AVENTIS SECURITIES ARE STRONGLY ADVISED TO READ THE
REGISTRATION STATEMENT AND THE PROSPECTUS AND PROSPECTUS SUPPLEMENT RELATING TO
THE REVISED OFFER, THE STATEMENT ON SCHEDULE TO, AND ANY OTHER RELEVANT
DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS AND SUPPLEMENTS BECAUSE
THEY CONTAIN IMPORTANT INFORMATION. Investors and holders of Aventis securities
may obtain free copies of the registration statement, the prospectus, the
prospectus supplement relating to the revised offer and related exchange offer
materials, and the Statement on Schedule TO, as well as other relevant documents
filed with the SEC, at the SEC's web site at www.sec.gov. The prospectus, the
prospectus supplement relating to the revised offer and other
transaction-related documents are being mailed to Aventis securityholders
eligible to participate in the U.S. offer and additional copies may be obtained
for free from MacKenzie Partners, Inc., the information agent for the U.S.
offer, at the following address: 105, Madison Avenue, New York, New York 10016;
telephone 1-(212) 929-5500 (call collect) or 1-(800) 322-2885 (toll-free call);
e-mail proxy@mackenziepartners.com.


                                     * * * *


                                                        [SANOFI-SYNTHELABO LOGO]


[graphic] Investor Relations



                      SANOFI-SYNTHELABO'S OFFER FOR AVENTIS
                      ADJUSTMENT OF OFFER TERMS ON APPROVAL
                               OF AVENTIS DIVIDEND



PARIS, FRANCE-- JUNE 14, 2004-- Sanofi-Synthelabo (PARIS: SAN, NYSE: SNY)
announces that at the Aventis (PARIS: AVE, FRANKFURT: AVE.ETR, NYSE: AVE) annual
general meeting held on June 11, 2004, the shareholders of Aventis voted to
approve Aventis's 2003 dividend in the amount of (euro)0.82 per share, with an
ex-dividend date of June 15, 2004 and a payment date of July 15, 2004.

As a result, in accordance with the terms of Sanofi-Synthelabo's revised offer
for Aventis, the terms of Sanofi-Synthelabo's offer for Aventis have been
adjusted in the following manner:

o      Standard entitlement: 5 Sanofi-Synthelabo ordinary shares and
       (euro)115.08 in cash for 6 Aventis ordinary shares (or 0.8333 of a
       Sanofi-Synthelabo ordinary share and (euro)19.18 in cash for each Aventis
       ordinary share; and 1.6667 Sanofi-Synthelabo ADSs and an amount in U.S.
       dollars equal to (euro)19.18 in cash for each Aventis ADS)

o      All stock election: 1.1600 Sanofi-Synthelabo ordinary shares for each
       Aventis ordinary share (or 2.3200 Sanofi-Synthelabo ADSs for each Aventis
       ADS)

o      All cash election: (euro)68.11 in cash for each Aventis ordinary share
       (or an amount in U.S. dollars equal to (euro)68.11 in cash for each
       Aventis ADS).

This adjustment is more fully described in Section 1.3.2(a) "Terms of the New
Offer for Aventis Shares" in the French prospectus supplement that obtained the
AMF's visa (no. 04-384) on May 7, 2004 and under the section entitled "The
Revised U.S. Offer -- Consideration Offered after Approval of Aventis Dividends"
in the U.S. prospectus supplement dated May 27, 2004.




In accordance with article 7 of the COB rule no. 2002-04, this press release was
transmitted to the Autorite des marches financiers (AMF) before its publication.

IMPORTANT INFORMATION: In connection with the proposed acquisition of Aventis,
Sanofi-Synthelabo has filed a registration statement on Form F-4 (File no.
333-112314), including a prospectus and a prospectus supplement relating to the
revised offer, and will file additional documents with the SEC. INVESTORS ARE
URGED TO READ THE REGISTRATION STATEMENT, INCLUDING THE PROSPECTUS AND THE
PROSPECTUS SUPPLEMENT RELATING TO THE REVISED OFFER, AND ANY OTHER RELEVANT
DOCUMENTS FILED WITH THE SEC, INCLUDING ALL AMENDMENTS AND SUPPLEMENTS, BECAUSE
THEY CONTAIN IMPORTANT INFORMATION. Free copies of the registration statement,
as well as other relevant documents filed with the SEC, may be obtained at the
SEC's web site at www.sec.gov. The prospectus and the prospectus supplement
relating to the revised offer and other transaction-related documents are being
mailed to Aventis security holders eligible to participate in the U.S. offer and
additional copies may be obtained for free from MacKenzie Partners, Inc., the
information agent for the U.S. offer, at the following address: 105, Madison
Avenue, New York, New York 10016; telephone: 1-(212) 929-5500 (call collect) or
1-(800) 322-2885 (toll-free call); e-mail proxy@mackenziepartners.com.

In France, holders of Aventis securities are requested, with respect to the
offer, to refer to the prospectus supplement (note d'information
complementaire), which has been granted visa number 04-384 by the Autorite des
marches financiers ("AMF") and which is available on the website of the AMF
(www.amf-france.org) and without cost from: BNP Paribas Securities Services,
GIS-Emetteurs, Service Logistique, Les Collines de l'Arche, 75450 Paris Cedex 9
and to the recommendation statement (note d'information en reponse) which has
been granted visa number 04-510.

The public offer to holders of Aventis ordinary shares located in Germany (the
"German Offer") is being made in accordance with applicable German law and
pursuant to an offer document/sales prospectus, which is available free of
charge at BNP Paribas Securities Services, Gruneburgweg 14, D-60322 Frankfurt am
Main (Fax: 069 - 152 05 277) and on the website of the Company
(www.sanofi-synthelabo.com). Any decision to tender Aventis ordinary shares in
exchange for Sanofi-Synthelabo ordinary shares under the German Offer must be
taken exclusively with regard to the terms and conditions of the German Offer,
as well as with regard to the information included in the offer document/sales
prospectus, including any amendments thereto, issued in Germany.

The French Offer, the U.S. Offer and the German Offer are being made on
substantially the same terms and completion of these offers is subject to the
same conditions. It is intended that the three offers will expire at the same
time.

Investors and security holders may obtain a free copy of the Form 20-F filed
with the SEC on April 2, 2004 and any other documents filed by Sanofi-Synthelabo
with the SEC at www.sec.gov as well as of the Reference Document filed with the
AMF on April 2, 2004 (No. 04-0391) at www.amf-france.org or directly from
Sanofi-Synthelabo on our web site at: www.sanofi-synthelabo.com.


INVESTOR RELATIONS DEPARTMENT
Philippe Goupit        Director of Investor Relations
Arnaud Delepine        Investor Relations Europe
Sanjay Gupta           Investor Relations US
Anne d'Halluin-Sulzer  Investor Relations

CONTACTS:
Email: investor-relations@sanofi-synthelabo.com
Europe                      US
Tel: + 33 1 53 77 45 45     Tel:  + 1 212 551 40 18
Fax: + 33 1 53 77 42 96     Fax:  + 1 646 487 40 18