Charles River and the Jackson Laboratory Cooperate in International Supply of Mouse Research Models.

Business Editors and Health/Medical Writers

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WILMINGTON, Mass. & BAR HARBOR, Maine--(BW HealthWire)--July 13, 2001

Charles River Laboratories International, Inc. (NYSE: CRL), through its wholly-owned subsidiary Charles River Laboratories, Inc., and The Jackson Laboratory today announced that the organizations have entered into a cooperative agreement, effective August 1, 2001, to supply The Jackson Laboratory's JAX(R) Mice to biomedical researchers located in European and Pacific Rim countries for all JAX(R) Mice strains, as well as to breed selected, high demand JAX(R) Mice strains, under The Jackson Laboratory's guidance, in local CRL breeding facilities in Europe and Japan.

The Jackson Laboratory will continue directly supplying JAX(R) Mice to researchers in the United States and other parts of the world. To minimize disruption to research progress, this new agreement allows for continued direct distribution to all researchers around the world and through currently used import agents during a transition period of a few months.

About The Jackson Laboratory

Established in 1929, The Jackson Laboratory is a not-for-profit, independent research institution with the mission to improve the quality of human life through discoveries arising from its own genetic research and by enabling the research and education of others. With over 1000 employees (including over 100 Ph.D. level scientists), the Laboratory has facilities for research, training and mouse production in Bar Harbor, Maine and also has a facility associated with the University of California, Davis campus. In addition to supplying "gold standard," genetically defined, inbred JAX(R) Mice strains, the Laboratory also serves as an international resource for mouse models of human disease. In this role the Laboratory continually develops, imports, breeds, characterizes, cryopreserves and supplies the world's broadest offering of unique specialty strains, called JAX(R) GEMM(TM) Strains. Dedicated to sharing knowledge and resources, the Laboratory also provides custom breeding, strain development, surgeries, cryopreservation and other research support services.

About Charles River Laboratories

Charles River Laboratories, based in Wilmington, Massachusetts, is a leading provider of critical research tools and integrated support services that enable innovative and efficient drug discovery and development. The Company is the global leader in providing the animal research models required in research and development for new drugs, devices and therapies. The Company also offers a broad and growing portfolio of biomedical products and services that enable customers to reduce cost, increase speed, and enhance productivity and effectiveness in drug discovery and development. Charles River's customer base spans over 50 countries, and includes all of the major pharmaceutical and biotechnology companies, as well as many leading hospitals and academic institutions. The Company operates 76 facilities in 15 countries worldwide.

This document may contain "forward-looking statements." Such statements involve a number of risks and uncertainties that could cause actual results to differ materially from those stated or implied by the forward looking statements, including risks specific to the matters described herein, such as failure to meet contractual performance requirements, changes in legislative and regulatory rules and restrictions governing the use of animal research models, opposition of special interest groups, intellectual property matters, and other general risks impacting the business of Charles River that are described in the Risk Factors contained in Charles River's periodic filings with the SEC, including Form S-3 filed on July 5, 2001. Charles River disclaims any intent or obligation to update forward-looking statement, and otherwise claim the safe harbor protections for forward-looking statement afforded under the Private Securities Litigation Reform Act of 1995.