Tokyo – London, 24 May 2005 -- Today Sosei Co. Ltd. [4565, Tokyo Stock Exchange MOTHERS index], a leading Japanese biopharmaceutical company, is pleased to announce its adoption of a “ Company with Committees” system. This adoption will be resolved by the decision at the General Shareholder’ s Meeting to be held on 29 June 2005 in Tokyo.

1. Purpose of Adoption of a “ Company with Committees” system Sosei aims to grow its corporate value by extending the transparency and objectivity of the company’ s operation and has recognised that corporate governance is one of the highest priorities of the management. At present, four directors out of the sevenmember Board do not have executive positions within the company, and three out of the four are external directors. Three directors also serve as Sosei executives who conduct business operations. Four non-executive directors are chosen based on their extensive experience and knowledge concerning corporate management and the pharmaceutical/biotechnology business. David Chiswell has been appointed as nonexecutive chairman for stronger supervision of the Board.

By adopting a “ Company with Committees” system, the company intends to enhance the corporate governance by distinguishing and developing the supervisory function of the Board and the operational function of the Executive Officers.

2. Candidate Directors of the Board

Name                                   New appointment                                          Current appointment

David CHISWELL                Chairman of the Board                                    Chairman of the Board

Shinichi TAMURA                Board Director                                                 Representative Director, President & CEO

Yoshiyuki YAMAKAWA        Board Director                                                 Representative Director, Executive Vice President & CFO

Hiroyuki HANADA                Board Director                                                 (new for the Board)  Senior Vice President, R&D

Kenzo NAKAJIMA                Board Director                                                 Board Director

Mark RICHMOND                 External Director                                             External Director

Takuya FUJII                        External Director                                             (new for the Board)  Representative of f Business Brain

3. Retirement from the Board

Name                                  Current appointment

Yuzo TARUMI                     Board Director, Executive Vice President

Edmund M. OLIVIER          External Director

4. Candidates for Executive Officers

Name                                 New appointment                                                                  Current appointment

Shinichi TAMURA              Representative Executive Officer, President & CEO              Representative Director, President & CEO

Yoshiyuki YAMAKAWA      Representative Executive Officer,                                          Representative Director, Executive Vice President & CFO

                                           Executive Vice President & CFO  

Hiroyuki HANADA              Executive Officer, Executive Vice President, R&D                (new for the Board) Senior Vice President, R&D

5. Introduction of New Candidates for the Board

Hiroyuki HANADA

Mr. Hanada joined Sosei in April 2005 as Senior Vice President of Research and Development. He has extensive experience in licensing and clinical development.

- Ex-Director and General Manager of R&D Dept. at Seikagaku Corporation

- Formerly worked for Hisamitsu Pharmaceutical Co., Inc., holding posts at Clinical Development and Licensing

- B.S. in Biochemistry from Kyushu University

Takuya FUJII

- Representative of f Business Brain

- Ex-Chairman and Representative of Marsh & McLennan Companies, Japan

- Former President & CEO of Nippon Credit Bank

- Former Chief Cashier in Bank of Japan

- MBA from the Wharton School of the University of Pennsylvania

- BA of Economics from Tokyo University

6. Effective Date 29 June 2005