Charles River Laboratories Receives FDA Approval for Sale and Marketing of First Portable Endotoxin Test System, the Endosafe-PTS(TM); Breakthrough One-Button Technology Revolutionizes Endotoxin Detection.

WILMINGTON, Mass. -- Charles River Laboratories International, Inc. (NYSE:CRL) has received FDA approval that allows for the sale and marketing of the first portable endotoxin test system, the Endosafe-PTS(TM). The patented Endosafe-PTS(TM) is used to detect endotoxin contaminants in drugs, medical devices, biological products and other unique applications including NASA spacecraft missions. The PTS is a revolutionary technology that:

--is a portable handheld system that can be used for point of use testing

--provides quantitative results in 15 minutes rather than current methods which take from 45 minutes to several days

--requires minimal technical training - just insert the PTS cartridge, add sample and read quantitative results

The Endosafe-PTS(TM) system can accelerate the discovery and development of new drugs by offering quick and easy endotoxin contamination results, thereby saving pharmaceutical companies, medical professionals and scientists both time and money in the manufacturing process.

Real world applications for the PTS system include:

--Medical devices & injectable drugs

--Dialysis clinics

--Nuclear medicine

--Hospitals

--Stem cell research

--Planetary protection

The PTS utilizes disposable cartridges that are pre-loaded with reagents and a portable, handheld reader to provide quantitative endotoxin amounts. Because of its portability, the PTS allows for testing to be performed at the point of sample collection. In addition, the simple one-button operation requires minimal technical training and the data can be stored in the PTS, downloaded to a computer and/or printed.

NASA recently used the Endosafe-PTS(TM) to monitor the environment for microbial contamination during the construction of the Mars exploration rovers "Spirit" and "Opportunity". PTS units are scheduled to be flown to the International Space Station to perform environmental monitoring for microbial contamination. Future applications of PTS may include detecting signs of microbial life on Mars.

About Charles River Laboratories

Charles River Laboratories, based in Wilmington, Massachusetts, U.S., 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 and many biotechnology companies, government agencies and leading hospitals and academic institutions. Charles River's 8,500 employees serve clients in more than 50 countries. For more information on Charles River, visit our website at www.criver.com.

Caution Concerning Forward-Looking Statements. This news release 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," "will," "may," "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 include the statements in this notice regarding Charles River's expectation regarding the markets for and potential applications of the PTS systems. Charles River cannot guarantee that the markets for PTS will develop as expected, or that specific applications of the PTS system will be viable. Forward-looking statements are based on Charles River's current expectations and beliefs, and involve a number of risks and uncertainties that are difficult to predict and that could cause actual results to differ materially from those stated or implied by the forward-looking statements. 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 14, 2006, as well as other filings we make with the Securities and Exchange Commission. Charles River assumes no obligation and expressly disclaims any duty to update information contained in this release except as required by law.