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 April, 2003

                                  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 logo


Media Release


FOR IMMEDIATE RELEASE



                 SERONO ANNOUNCES INCREASED OWNERSHIP OF GENSET


GENEVA, Switzerland-April 15, 2003- Serono S.A. (Virt-x: SEO, NYSE: SRA)
announced today that Serono France Holding S.A. now holds 19,371,449 Genset S.A.
shares or 96.60% of its capital and voting rights. This is a result of the
settlement/delivery today of the shares issued in the capital increase with
preferential subscription rights which was launched by Genset S.A. in March
2003.

Consistent with its prior announcements in this respect, and subject to the
satisfactory completion of the necessary steps with the French market
authorities, Serono France Holding S.A. has decided to launch, shortly, a
repurchase offer followed by a mandatory squeeze-out with respect to outstanding
Genset S.A. equity securities.


                                      ###

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 May 21 2002. 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.



                                       ###



                                     -more-


About Serono

Serono is a global biotechnology leader. The Company has six recombinant
products on the worldwide market, Gonal-F(R) (follitropin alfa for injection),
Luveris(R) (lutropin alfa), (Luveris(R) is not approved in the USA.),
Ovidrel(R)/Ovitrelle(R) (choriogonadotropin alfa for injection), Rebif(R)
(interferon beta-1a), Serostim(R) [somatropin (rDNA origin) for injection] and
Saizen(R) [somatropin (rDNA origin) for injection]. 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 over 30 projects in development.

Serono was awarded the International James D. Watson Helix 2003 Award from the
Biotechnology Industry Organization (BIO) in recognition of the Company's
outstanding leadership and highest standards of scientific and product
achievement.

In 2002, Serono achieved worldwide revenues of US$1.546 billion, and a net
income of US$321 million, making it the third largest biotech company in the
world. The Company operates in 45 countries, and its products are sold in over
100 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).



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

-end-



                                   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)



April 21, 2003                     By:   /s/ Allan Shaw
                                         ------------------------------
                                         Name: Allan Shaw
                                         Title: Chief Financial Officer