Charles River Laboratories' Endosafe - PTS Completes Journey to the International Space Station

Charles River Laboratories International, Inc. (NYSE:CRL) announces that its portable endotoxin testing system, the Endosafe - PTS[tm], was recently launched into space aboard the space shuttle Discovery and successfully reached the International Space Station as part of NASA's ongoing efforts to conduct biological research in space.

The Endosafe-PTS[tm] is a handheld endotoxin detection system that was licensed by the FDA in July 2006 and is currently in use in pharmaceutical and biotechnology facilities around the world as a release method for drug products due to its ease-of-use and rapid results.

The system is a point-of-use application that includes a handheld reader and disposable cartridge preloaded with all of the reagents to perform the test. The reader incubates the samples and reads the optical density to provide quantitative endotoxin results in about 15 minutes. The PTS[tm] is designed to eliminate subjectivity and interpretation of results, and up to 100 results can be saved in memory and downloaded to lab management software.

The PTS[tm] was modified for spaceflight by Charles River Laboratories in collaboration with NASA's Marshall Space Flight Center (MSFC) science team, Lab-on-a-Chip Application Development (LOCAD), and Carnegie Institution of Washington. The LOCAD-PTS will help astronaut-scientists perform biological studies necessary for an extended human presence in space, from crew health and spacecraft environmental studies to the search for life elsewhere in the solar system.

Initially, it will provide rapid analysis to determine if certain types of bacteria are present on various space station surfaces. In the future, interchangeable system components will enable station crews to monitor their environment for contaminants such as yeast, mold and, eventually, more virulent and potentially harmful bacteria -- such as E. coli and Salmonella.

"The information gained from this flight demonstration will be used to develop even more mature technology, enabling researchers to perform thousands of tests simultaneously in the space environment," said Dr. Lisa Monaco, lead scientist at NASA's Marshall Space Flight Center." Such a platform will enable space-based explorers to perform environmental tests, conduct crew health studies and support the search for life on Mars."

The PTS[tm] reader is a platform that is used for other rapid micro methods, including Gram identification and protein determination.

"We are excited to be collaborating with NASA on this remarkable new application for the PTS[tm]. The PTS[tm] technology has opened many new avenues of research and development for us. What began as an innovative method for efficient detection of microbial contamination has now expanded to a broad array of rapid assays including monitoring environmental cleanliness and testing kidney dialysis units and cell transplantation materials. Future applications for the PTS[tm] could also include use in intensive care units for clinical diagnosis," explains Dr. Norman Wainwright, Director of Research and Development at Charles River Laboratories.

For more information on the Endosafe(r)-PTS[tm], please visit our web site at www.criver.com/pts or call 1-877-CRIVER-1.

"NASA Lab-on-a-Chip Technology Begins Journey to Space Station" press release, December 4, 2006.

About Charles River Laboratories Charles River Laboratories, based in Wilmington, Massachusetts, partners with global pharmaceutical and biotechnology companies, government agencies and leading academic institutions to advance the drug discovery and development process, bringing drugs to market faster and more efficiently. Charles River's 7,500 employees serve clients worldwide. For more information on Charles River, visit our web site 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. ### Charles River Laboratories

Contacts: Susan E. Hardy Corporate Vice President, Investor Relations (781)262-7616

Investors: Endosafe-PTS[tm]: Barbara Grady Sr. Marketing Manager (877)CRIVER-1