Exhibit 99.1 News Release BIO-RAD, SANOFI-SYNTHELABO AND INSTITUT PASTEUR SIGN DEFINITIVE AGREEMENT FOR THE ACQUISITION OF PASTEUR SANOFI DIAGNOSTICS HERCULES, CA Bio-Rad Laboratories, Inc. (AMEX: BIO.A and BIO.B) announced today the acceptance of its acquisition bid for Pasteur Sanofi Diagnostics (PSD) by Sanofi-Synthelabo S.A. and Institut Pasteur, the shareholders of PSD. According to the terms of the definitive agreement, Bio-Rad will acquire 100% of the shares of (and certain assets and assumed liabilities related to) PSD for a purchase price of $210,000,000. Financing has been committed by Banc One. Finalization of the transaction is expected within approximately ninety days to allow for financial arrangements and necessary regulatory review and clearance. Bio-Rad expects diagnostics sales to increase to approximately $400 million as a result of the acquisition, moving the Company into the top ten in the diagnostics industry. The composite portfolio of the combined organizations affords Bio-Rad the ability to provide products and services to the clinical laboratory across a broad spectrum of departments and disease states, including tests for blood virus, bacteriology, infectious disease, diabetes monitoring, genetic disease screening, and quality control management. The acquisition also includes a collaboration agreement with the Institut Pasteur, giving Bio-Rad a priority to commercialize Pasteur s discoveries in the In Vitro diagnostics market. Bio-Rad views this relationship as a significant competitive advantage in the infectious disease market and anticipates expanding the alliance towards the continued success of both organizations. Bio-Rad Laboratories President and CEO, David Schwartz said, This acquisition places us in a more favorable position in the diagnostics market. It gives us a significant presence in all key geographic areas, including the emerging economies, as well as a substantial product offering in market segments showing strong long-term growth. Bio-Rad Laboratories, Inc. (www.bio-rad.com) is a multinational manufacturer and distributor of life science research products, clinical diagnostics and analytical instrumentation, based in Hercules, California. The company serves more than 70,000 research and industry customers worldwide through a network of 25 wholly-owned subsidiary offices. For more information, contact: Contact: Tom Chesterman, Vice President and Chief Financial Officer Phone: (510) 741-6006 Email: tom_chesterman@bio-rad.com Date: July 5, 1999 For Release: 9 a.m. (P.S.T.)