SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    ________

                                    FORM 6-K

                        REPORT OF FOREIGN PRIVATE ISSUER
                      PURSUANT TO RULE 13a-16 OR 15d-16 OF
                       THE SECURITIES EXCHANGE ACT OF 1934

                         For the month of February, 2004

                                  Serono S.A.
                      -----------------------------------
                              (Registrant's Name)

                            15 bis, Chemin des Mines
                                Case Postale 54
                                CH-1211 Geneva 20
                                  Switzerland
                          -------------------------------
                    (Address of Principal Executive Offices)

                                    1-15096
                      -----------------------------------
                              (Commission File No.)

     (Indicate  by  check  mark whether the registrant files or will file annual
reports under cover of Form 20-F or Form 40-F.)

     Form  20-F  X Form  40-F
                ---           ---

     (Indicate  by  check  mark  if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(1).) ______

     (Indicate  by  check  mark  if the registrant is submitting the Form 6-K in
paper as permitted by Regulation S-T Rule 101 (b)(7).) ______

     (Indicate  by  check  mark  whether  the  registrant  by  furnishing  the
information contained in this form is also thereby furnishing the information to
the  Commission  pursuant to Rule 12g3-2(b) under the Securities Exchange Act of
1934.)

     Yes     No  X
         ---    ---

     (If  "Yes"  is  marked,  indicate  below  the  file  number assigned to the
registrant in connection with Rule 12g3-2(b): 82-______)



SERONO                                                                     INDEX
                                                              Pharmaceuticals AB



Media  Release


FOR  IMMEDIATE  RELEASE
-----------------------



            SERONO AND SWEDISH BIOTECH COMPANY INDEX PHARMACEUTICALS
              SIGN WORLDWIDE AGREEMENT TO DEVELOP AND COMMERCIALIZE
                       NOVEL ULCERATIVE COLITIS TREATMENT

       AGREEMENT FOR NOVEL GASTROENTEROLOGY THERAPY CURRENTLY IN PHASE II



GENEVA, SWITZERLAND AND STOCKHOLM, SWEDEN - FEBRUARY 24, 2004 -

Serono  (virt-x:  SEO  and  NYSE:  SRA)  and  InDex Pharmaceuticals AB ("InDex")
announced  today  that they have signed an agreement under which Serono receives
exclusive  worldwide  rights  to  develop  and  commercialize  InDex'  product
Kappaproct(R)  for  the  treatment  of  ulcerative colitis and potentially other
inflammatory  diseases.  Kappaproct(R)  is  an  antisense  inhibitor  of the p65
protein, a key activator of the pro-inflammatory NF-kappa B pathway.

Under  the  terms  of  the agreement, InDex will receive an initial fee upon the
effective  date  of  the  agreement  and potential milestone payments related to
development  progress, regulatory submissions and approvals, as well as research
and  development  funding.  If  Kappaproct(R)  is  successfully  developed  and
registered  worldwide  in at least one indication, the aggregate amount of these
payments  could  reach  USD35  million.  InDex  will  also  receive  undisclosed
royalties  on  sales  of  Kappaproct(R).

"Ulcerative colitis is a severe debilitating disease and represents a high unmet
medical  need,"  said  Franck Latrille, Serono's Senior Executive Vice President
Global Product Development. "Kappaproct(R) has the potential to be a significant
breakthrough  by  inducing clinical remission in patients with active ulcerative
colitis  without  compromising  safety."

"As one of the world's leading biotechnology companies, Serono has an impressive
track  record in the development and marketing of innovative therapeutics," said
Svante  Rasmuson, CEO of InDex Pharmaceuticals. "We are confident that in Serono
we  have found a strong and committed partner for completing development of this
novel  approach  to  the  treatment  of  ulcerative  colitis".


                                                                             1/3

Kappaproct(R)  is currently being tested in a Phase II clinical trial for active
ulcerative  colitis  which  will  involve  150  patients.  In  a  completed
proof-of-concept,  double-blind  placebo-controlled  clinical  trial in patients
with  therapy-resistant  inflammatory  bowel  disease,  it  was  shown  that the
majority  of  these  patients  responded  positively  to  a  single  dose  of
Kappaproct(R).  Patients  receiving  Kappaproct(R) experienced only mild adverse
effects.

Kappaproct(R)  is  being  developed  for  the treatment of ulcerative colitis, a
chronic  inflammatory  condition  involving the large bowel. This disease mainly
affects young people, with disease onset typically occurring between the ages of
20  and  30  years. The most common symptoms of ulcerative colitis are abdominal
discomfort  and  frequent  loose  stools.  Patients may also experience fatigue,
weight  loss,  loss  of  appetite,  rectal  bleeding,  loss  of  body fluids and
nutrients. Severely affected patients experience fever, bloody diarrhea, nausea,
and  abdominal cramps. Ulcerative colitis may also cause non-intestinal problems
such  as  arthritis,  inflammation of the eye, liver disease and anemia. Disease
management is a long-term commitment for both patient and physician, since there
is currently no cure for this condition. In a majority of cases, the disease may
be  controlled  with conventional drugs, including 5-aminosalicylic acid (5-ASA)
and  glucocorticosteroids.  However,  between  25  and  40 percent of ulcerative
colitis  patients  are  unresponsive  to  such treatment, and ultimately require
surgical  resection of the colon. Patients with long-standing ulcerative colitis
disease are at considerable risk of developing colorectal cancer.


                                       ###

Serono
Some  of  the  statements  in  this  press  release  are  forward  looking. Such
statements  are inherently subject to known and unknown risks, uncertainties and
other  factors  that  may  cause  actual results, performance or achievements of
Serono  S.A.  and  affiliates  to be materially different from those expected or
anticipated  in  the  forward-looking statements. Forward-looking statements are
based on Serono's current expectations and assumptions, which may be affected by
a  number  of  factors, including those discussed in this press release and more
fully  described  in  Serono's  Annual  Report  on Form 20-F filed with the U.S.
Securities and Exchange Commission on April 17, 2003.  These factors include any
failure  or  delay  in  Serono's ability to develop new products, any failure to
receive  anticipated  regulatory  approvals,  any  problems  in  commercializing
current  products  as  a  result of competition or other factors, our ability to
obtain  reimbursement  coverage  for  our  products,  and government regulations
limiting  our  ability  to  sell  our  products. Serono has no responsibility to
update the forward-looking statements contained in this press release to reflect
events or circumstances occurring after the date of this press release.

                                       ###



                                                                             2/3

ABOUT  SERONO

Serono  is  a  global  biotechnology  leader.  The Company has seven recombinant
products,  Rebif(R),  Gonal-F(R),  Luveris(R),  Ovidrel(R)/Ovitrelle(R),
Serostim(R), Saizen(R) and Zorbtive(TM) (Luveris(R) is not approved in the USA).
In  addition to being the world leader in reproductive health, Serono has strong
market  positions  in  neurology,  metabolism and growth. The Company's research
programs  are  focused  on  growing  these  businesses  and  on establishing new
therapeutic  areas.  Currently,  there  are approximately 30 ongoing development
projects.

In  2003,  Serono  achieved  worldwide revenues of US$2,018.6 million, and a net
income  of  US$390.0 million, making it the third largest biotech company in the
world. Its products are sold in over 90 countries. Bearer shares of Serono S.A.,
the  holding company, are traded on the virt-x (SEO) and its American Depositary
Shares are traded on the New York Stock Exchange (SRA).


ABOUT  INDEX  PHARMACEUTICALS

InDex  Pharmaceuticals develops antisense therapeutics and diagnostic/prognostic
tools  for  unmet  medical  needs  within  inflammation and cancer. The company,
located at Karolinska Institutet in Stockholm, was incorporated in December 2000
and has currently a staff of 26 people. Main shareholders are SEB Foretagsinvest
and  Life  Equity  Sweden.

The  company's  corporate mission is to break new ground in innovative therapies
and  thus  become  a  preferred  R&D  partner  to  large industry players in the
biopharmaceutical  area.  The  first  product  Kappaproct(R),  developed for the
treatment  of  inflammatory  bowel  disease,  has entered into phase II clinical
trials  for  active  ulcerative  colitis.

Research  activities  are  focused  on development of antisense drugs. Antisense
represents  an  expansion  of  conventional pharmacology in combination with new
findings  within  molecular biology. Consequently, a new class of drugs has been
created  with  a  different  approach,  but the antisense technology itself also
implies  a  more  rational  design  of  new  drugs.


FOR MORE INFORMATION, PLEASE CONTACT:

SERONO IN GENEVA, SWITZERLAND:
MEDIA  RELATIONS:                 INVESTOR  RELATIONS:
Tel:  +41-22-739 36 00            Tel:  +41-22-739 36 01
Fax:  +41-22-739 30 85            Fax:  +41-22-739 30 22
http://www.serono.com             Reuters:  SEOZ.VX / SRA.N
---------------------             Bloomberg:  SEO VX / SRA US

SERONO, INC., ROCKLAND, MA
MEDIA  RELATIONS:                 INVESTOR  RELATIONS:
Tel.   +1 781 681 2340            Tel.  +1 781 681 2552
Fax:   +1 781 681 2935            Fax:  +1 781 681 2912
http://www.seronousa.com
------------------------


INDEX PHARMACEUTICALS, STOCKHOLM, SWEDEN:
Tel:  +46-8-50 88 47 30
Fax:  +46-8-50 88 47 39
http://www.indexpharmab.com
---------------------------


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                                   SIGNATURES

     Pursuant  to  the  requirements of the Securities Exchange Act of 1934, the
registrant  has  duly  caused  this  report  to  be  signed on its behalf by the
undersigned,  thereunto  duly  authorized.



                                         SERONO S.A.
                                         a Swiss corporation
                                         (Registrant)



February 24, 2004                        By:   /s/ Allan Shaw
                                               ---------------------------
                                         Name:   Allan Shaw
                                         Title:  Chief Financial Officer