CAMBRIDGE, Mass. and FRANKFURT, Germany, June 23, 2000 -- Millennium Pharmaceuticals, Inc. (Nasdaq: MLNM) and Aventis Pharma, the pharmaceutical company of Aventis S.A. (NYSE: AVE), and today announced that they have formed a unique alliance with the signing of agreements covering the joint development and commercialization of drugs for the treatment of inflammatory diseases; joint development of new drug discovery technologies; transfer of key elements of Millennium's technology platform to Aventis to enhance its existing capabilities; and purchase of an equity interest in Millennium by Aventis. This is the first biotechnology/pharmaceutical company alliance of its kind, which will result in Millennium and Aventis Pharma working collaboratively to identify drug targets and develop new drugs in the field of inflammation and jointly commercialize the resulting products in North America.

The foundation for this alliance is the establishment of four separate arrangements covering Inflammation, Technology Development, Technology Transfer and an Equity Investment. Under a Technology Transfer Agreement, Millennium will provide Aventis with rights to its drug discovery technologies in exchange for payments of up to $200 million over a five-year period. Under an Equity Investment Agreement, Aventis will also invest $250 million in Millennium's common stock. A $150 million stock purchase will be made at closing and two $50 million purchases will be made in 2001. The combination of the Technology Transfer and the Investment Agreements represent a total of up to $450 million in payments to and investments in Millennium by Aventis. Both the Inflammation and Technology Development Agreements call for joint funding by the two companies. The closing may be subject to expiration or early termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.

Millennium and Aventis Pharma Form Novel Alliance to Develop and Commerc
'"/>

Contact: Sally McCraven, Millennium Pharmaceuticals, Inc.
617-577-3548
Porter Novelli
22-Jun-2000