Charles River Laboratories Reaffirms First-Quarter 2005 EPS Guidance.

WILMINGTON, Mass. -- Charles River Laboratories International, Inc. (NYSE: CRL) today reiterated that redemption of its $185 million, 3.50% Senior Convertible Debentures due February 1, 2022 is not expected to affect its previously disclosed earnings per share guidance. To the extent that holders of the Debentures convert to common stock, there will be no effect on earnings per share. For financial reporting purposes, the Company has always accounted for the Debentures as if they had been converted by including approximately 4.8 million shares in the fully diluted share count.

The Company is reaffirming its first-quarter sales growth and earnings per share guidance, which was previously announced on February 14, 2005. At that time, the Company said that sales growth for the first quarter of 2005 was expected to be in a range of 57% to 60% and that earnings per diluted share were expected to be in a range of $0.39 to $0.41. On a non-GAAP basis, excluding charges related to the merger with Inveresk Research Group of $13.3 million of amortization and a $2.7 million compensation charge, earnings per diluted share were expected to be in a range of $0.54 to $0.56.

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," "outlook," and "project" and other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. Forward-looking statements are based on Charles River's current expectations and beliefs, 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. Those risks and uncertainties include, but are not limited to: challenges arising from the merger with Inveresk Research Group; a decrease in 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; 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 tax regulation and laws; 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 Charles River's Annual Report on Form 10-K as filed on March 9, 2005, with the Securities and Exchange Commission. Because forward-looking statements involve risks and uncertainties, actual results and events may differ materially from results and events currently expected by Charles River, and Charles River assumes no obligation and expressly disclaims any duty to update information contained in this news release except as required by law.

About Charles River Laboratories

Charles River Laboratories, based in Wilmington, Massachusetts, is a global provider of solutions that advance the drug discovery and development process. Our leading-edge products and services are designed to enable our clients to bring drugs to market faster and more efficiently. Backed by our rigorous, best-in-class procedures and our proven data collection, analysis and reporting capabilities, our products and services are organized into three categories spanning every step of the drug development pipeline: Research Models and Services, Preclinical Services, and Clinical Services. Charles River's customer base includes all of the major pharmaceutical companies, biotechnology companies, government agencies and many leading hospitals and academic institutions. Charles River's 8,000 employees serve clients in more than 50 countries. For more information on Charles River, visit our website at www.criver.com.