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 25, 2004


         On June 25, 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 AND PFIZER CONCLUDE AN AGREEMENT
                   ON THE DIVESTMENT OF CAMPTO(R) (IRINOTECAN)
                           CONDITIONAL UPON COMPLETION
                    OF SANOFI-SYNTHELABO'S OFFER FOR AVENTIS


PARIS, JUNE 25, 2004 -  Sanofi-Synthelabo  announced today that it has signed an
agreement  with Pfizer Inc.  regarding the  divestment of Aventis'  interests in
Campto(R)   (irinotecan)  in  response  to  requests  made  by  the  competition
authorities.

Subject to the  consent of the US Federal  Trade  Commission  and the success of
Sanofi-Synthelabo's  offer for  Aventis,  Pfizer  will  take  over key  clinical
studies for  Campto(R)  that are currently  conducted by Aventis,  together with
certain  patents  and  other  assets  pertaining  to  territories  where  Pfizer
currently markets irinotecan,  including the United States. Pfizer will further,
subject  to certain  conditions  including  clearance  by  European  competition
authority, acquire all other assets relating to Campto(R) held by Aventis.

The  consideration  for the whole  transaction  is of $ 620 million and includes
some milestone payments for the registration of future indications.

Campto(R)  (irinotecan) is indicated for treatment of advanced colorectal cancer
in  combination  with  5-fluorouracil  (FU) and folinic acid (FA) in  first-line
treatment as well as  monotherapy in  second-line  treatment.  Several Phase III
studies are  underway or have  recently  been  completed  to evaluate the use of
Campto(R)  in adjuvant  chemotherapy  in  colorectal  cancer,  advanced  gastric
cancer, small cell lung cancer, and non-small-cell lung cancer.

Aventis markets Campto(R), which was first launched in 1995 under a license from
Yakult Honsha Company Limited,  primarily in Europe,  Asia and Africa.  In 2003,
Aventis' sales of Campto(R) reached (euro) 264 million.




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:
E-mail: 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