Exhibit 99.1

                   Charles River Laboratories to Redeem 3.50%
                     Senior Convertible Debentures Due 2022


    WILMINGTON, Mass.--(BUSINESS WIRE)--March 28, 2005--Charles River
Laboratories International, Inc. (NYSE: CRL) today announced that it
has called for redemption all of its $185 million, 3.50% Senior
Convertible Debentures due February 1, 2022. Notices of redemption are
being mailed to holders of the Debentures today.
    The redemption date has been set at April 19, 2005. The Debentures
are convertible into shares of Charles River's common stock at a
conversion price of $38.87. The Debentures may be converted at any
time before the close of business on April 18, 2005. On April 19,
2005, Charles River will pay all remaining principal balances that
have not been previously converted into common stock, plus the
applicable 0.875% prepayment premium and any accrued and unpaid
interest, up to but not including the redemption date, in cash. To the
extent that any holders do not convert prior to the redemption date,
or the Company is required to pay for fractional shares, payment for
any debentures redeemed or fractional shares will be made from cash
generated by operations.
    James C. Foster, Chairman, President and Chief Executive Officer
said, "We are calling the Debentures at this time in order to achieve
two goals: to reduce interest expense and improve our debt to equity
ratio. We believe that by doing so, we further strengthen our balance
sheet and free up cash, formerly used for debt service, which we can
deploy more effectively elsewhere in the business."
    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.

    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.



    CONTACT: Charles River Laboratories
             Susan E. Hardy, 978-658-6000 Ext. 1616
             Director, Investor Relations