BioSource International Is Pleased to Announce the Appointment of John L. Zabriskie, Ph.D. to the Board of Directors.

Business Editors

BioSource International, Inc. (Nasdaq:BIOI), announces today the appointment of a new Board of Directors member, John L. Zabriskie, Ph.D. Dr. Zabriskie is the President of Lansing Brown Investments and is the past Chairman to the Board of Directors, Chief Executive Officer and President of NEN Life Science Products, Inc. a leading supplier of kits for labeling and detection of DNA. He was also President and Chief Executive Officer of Pharmacia and Upjohn, Inc. a Fortune 500 pharmaceutical company formed by the merger of Pharmacia AB of Sweden and the Upjohn Company of Kalamazoo, Michigan. As Chairman of the Board and Chief Executive Officer of the Upjohn Company, Dr. Zabriskie led the Upjohn project, which resulted in the $12 billion merger of equals.

Prior to joining Upjohn in 1994, Dr. Zabriskie was Executive Vice President of Merck and Co., Inc. He began his career at Merck as a chemist in 1965. He held a variety of positions in quality control, manufacturing and marketing, including, from 1983 to 1988, President of Merck Frosst Canada, Inc., from 1988 to 1991, President of Merck Sharp & Dohme, and from 1991-1992 Senior Vice President of Merck and President, Merck Manufacturing Division.

Dr. Zabriskie was a member of the U.S. Healthcare Leadership Council. He has served on a number of boards for health care and academic institutions and currently serves on the Kellogg Co., Cubist Pharmaceutical, Inc., Biomira, Inc., Array BioPharma, Mimeon, Puretech Ventures and MacroChem Corp. boards. Dr. Zabriskie is a native of Aurora N.Y. and received his A.B. degree in chemistry from Dartmouth College (N.H.) in 1961 and his Ph.D. in organic chemistry from the University of Rochester (N.Y.) in 1965.

Len Hendrickson, President & CEO said, "We are delighted that John is joining our Board. He has broad and deep experience in drug discovery and associated reagents markets, and we look forward to his contributions to BioSource."

BioSource International, Inc. is a broad based life sciences company focused on providing integrated solutions in the areas of functional genomics, proteomics, and drug discovery through the development, manufacturing, marketing and distribution of unique biologically active reagent systems which facilitate, enable and accelerate pharmaceutical development and biomedical research.

This press release contains statements about expected future events that are forward-looking and subject to risks and uncertainties. For these statements, we claim the safe harbor for "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Factors that could cause actual results to differ and vary materially from expectations include, but are not limited to, our ability to expand our product offerings and any transition to new products, product quality and availability, any change in business conditions, changes in our sales strategy and product development plans, competitive pricing pressures, continued market acceptance of our products, name recognition of our products, delays in the development of new technology, intellectual property and proprietary rights may not be valid or infringe the rights of others, changes in customer buying patterns issues, one-time events and other important factors disclosed previously and from time to time in our filings with the Securities and Exchange Commission. These cautionary statements by us should not be construed as exhaustive or as any admission regarding the adequacy of disclosures made by us. We cannot always predict or determine after the fact what factors would cause actual results to differ materially from those indicated by the forward-looking statements or other statements. In addition, readers are urged to consider statements that include the terms "believes," "belief," "expects," "plans," "objectives," "anticipates," "intends," "targets," "projections," or the like to be uncertain and forward-looking. All cautionary statements should be read as being applicable to all forward-looking statements wherever they appear. We do not undertake any obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.