PROSPECTUS SUPPLEMENT NO. 4 TO PROSPECTUS DATED APRIL 24, 2002

                 CHARLES RIVER LABORATORIES INTERNATIONAL, INC.


                                  $185,000,000
            3.50% SENIOR CONVERTIBLE DEBENTURES DUE FEBRUARY 1, 2022
                                       AND
             COMMON STOCK ISSUABLE UPON CONVERSION OF THE DEBENTURES

                               -------------------

     This prospectus supplement will be used by the holders of debentures listed
below to resell their debentures or the shares of our common stock, par value
$0.01 per share, issuable upon conversion of the debentures.

     You should read this prospectus supplement together with the prospectus
dated April 24, 2002, which is to be delivered with this prospectus supplement.

     The table below sets forth additional and updated information concerning
beneficial ownership of the debentures, and supplements and, to the extent
inconsistent with, amends the table appearing under the caption "Selling
Securityholders" beginning on page 32 of the prospectus. To the extent that a
selling securityholder is listed both in the table below and in the table
appearing in the prospectus, the information set forth below regarding that
selling securityholder supersedes the information set forth in the prospectus.
We have prepared this table based on information given to us by the selling
securityholders listed below prior to the date hereof.




                                                PRINCIPAL                            NUMBER OF
                                                AMOUNT OF                            UNDERLYING
                                                DEBENTURES       PERCENTAGE OF       SHARES OF       PERCENTAGE OF
                                              OWNED AND THAT      DEBENTURES        COMMON STOCK      COMMON STOCK
NAME                                           MAY BE SOLD        OUTSTANDING     THAT MAY BE SOLD  OUTSTANDING (1)
- ----------------------------------            --------------     -------------    ----------------  ---------------
                                                                                        
Atlantic Trust Company                           2,500,000            1.35%           64,316.95            *
UBS O'Connor, LLC F/B/O UBS Global
   Convertible Portfolio                           500,000              *             12,863.39            *



- ------------------
*    Less than 1%

(1)  Calculated based on Rule 13d-3(d)(1)(i) of the Exchange Act using
     44,745,339 shares of common stock outstanding as of July 31, 2002. In
     calculating this amount for each holder, we treated as outstanding the
     number of shares of common stock issuable upon conversion of all of that
     holder's debentures, but we did not assume conversion of any other holder's
     debentures.

                               -------------------

     INVESTING IN THE DEBENTURES INVOLVES RISKS THAT ARE DESCRIBED IN "RISK
FACTORS RELATING TO OUR DEBT" BEGINNING ON PAGE 9 OF THE PROSPECTUS.

     NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED THESE SECURITIES, OR DETERMINED IF THIS
PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

            THE DATE OF THIS PROSPECTUS SUPPLEMENT IS AUGUST 13, 2002