Charles River Laboratories Updates Outlook for 2003.

Business Editors/Health/Medical Writers

BIOWIRE2K

WILMINGTON, Mass.--(BUSINESS WIRE)--Sept. 2, 2003

Charles River Laboratories International, Inc. (NYSE:CRL) today announced updated guidance for the third-quarter and full-year 2003. For the third quarter, at current exchange rates, the Company now expects revenue growth in a range of 6-9% over the third quarter of 2002 and earnings per diluted share to be in the range of $0.39 to $0.41. This compares to the Company's earlier guidance of revenue growth in a range of 12-14% and earnings per diluted share of $0.42 to $0.44.

For the full year, at current exchange rates, revenue is expected to grow in a range of 9-11% and earnings per diluted share are expected to be between $1.58 and $1.63.

James C. Foster, Chairman, President and Chief Executive Officer said, "Our revised guidance for the third quarter and full year reflects slower growth in demand for our research models and transgenic services. We believe the recent slower growth, which became more pronounced as the third quarter progressed, is the result of pharmaceutical mergers, tighter pharma spending, and continuing financing pressures among small to mid-size biotechnology companies. In addition, the research models business typically experiences seasonality in the summer, and this year, that seasonality appears more pronounced. Also, our European results have been negatively affected by a strengthening dollar. On the positive side, the balance of our portfolio is performing well, including our development services business which continues to improve. Despite lower-than-expected sales, we expect the full-year operating margin to remain strong at approximately 22%, yielding a significant increase in cash flow, in line with our prior guidance."

Mr. Foster added, "From a long-term perspective, we continue to see our business strongly positioned as a leading provider to the pharmaceutical and biotechnology industries. Our portfolio of businesses provides pharma and biotech companies the products and services which are essential to their drug discovery and development effort."

The Company will host a conference call to discuss this press release on Wednesday, September 3, at 8:45 a.m. EDT. To participate in the conference call, please call [phone]. International participants should call [phone]. A live webcast of the conference call will be available at ir.criver.com. The webcast replay will be available approximately two hours after the conference call and will remain available until September 5, 2003.

In addition, the Company will discuss this press release at its presentation at the Thomas Weisel Healthcare Tailwinds Conference in Boston on Wednesday, September 3, at 11:45 a.m. EDT. A live webcast of the Company's presentation will be available at ir.criver.com. The webcast replay will be available approximately two hours after the presentation and will remain available until September 10, 2003.

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 companies, biotechnology companies, and many leading hospitals and academic institutions. The Company operates 82 facilities in 16 countries worldwide.

Caution Concerning Forward-Looking Statements. This document includes "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by the use of words such as "anticipate," "believe," "expect," "estimate," "plan," and "project" and other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. These statements are based on management's current expectations, and 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, and the Company expressly does not undertake any duty to update forward-looking statements, which speak only as of the date of this document. Those risks and uncertainties include, but are not limited to: a decrease in pre-clinical research and development spending or a decrease in the level of outsourced services; acquisition integration risks; special interest groups; contaminations; industry trends; new displacement technologies; outsourcing trends; USDA and FDA regulations; changes in law; continued availability of products and supplies; loss of key personnel; interest rate and foreign currency exchange rate fluctuations; changes in generally accepted accounting principles; and any changes in business, political, or economic conditions due to the threat of future terrorist activity in the U.S. and other parts of the world, and related U.S. military action overseas. A further description of these risks, uncertainties, and other matters can be found in the Risk Factors detailed in the Company's Annual Report on Form 10-K as filed on March 20, 2003, with the Securities and Exchange Commission.