BioSource International Inc., Announces Settlement of Arbitration.

Business Editors/Biotechnology Writers

BioSource International, Inc. (NASDAQ:BIOI), announced today that it has settled its Arbitration Claim against the QCB Claims Committee and the Principal Shareholders of Quality Controlled Biochemicals, Inc.

On December 9, 1998, BioSource International, Inc., entered into a Stock Purchase Agreement for the shares of Quality Controlled Biochemicals, Inc., of Hopkinton, Massachusetts.

Pursuant to that agreement, $1,347,000, was held in escrow. BioSource had entered into an arbitration proceeding as a result of a dispute following the closing of the sale.

The parties have settled the dispute and signed a Settlement Agreement. Pursuant to the terms of that agreement BioSource will receive $800,000 of the escrowed Funds and the QCB Claims Committee and the Principal Shareholders will receive the residual and accrued interest, approximately $750,000.

Len Hendrickson, President and CEO of BioSource, said, "We are introducing an exciting range of cytokine and signal transduction products, and we are pleased to have this arbitration matter behind us so we can focus totally on making BioSource successful in these growing markets."

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 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.