PROSPECTUS SUPPLEMENT (TO PROSPECTUS DATED SEPTEMBER 5, 2000) Charles River Laboratories International, Inc. Common Stock Warrants to Purchase Common Stock - ------------------------------------------------------------------------------- We initially issued the warrants in a transaction exempt from the registration requirements of the Securities Act of 1933. Each warrant entitles the holder to purchase 7.60 shares of our common stock at an exercise price of $5.19 per share, subject to adjustment in some circumstances. We filed a registration statement (Registration No. 333-92383) in order to permit the holders of these warrants and shares of our common stock acquired on exercise of these warrants to resell those securities in transactions that are registered under the Securities Act of 1933. On pages 52 through 55 of the prospectus contained in that registration statement, there is a table that provides certain information with respect to those holders. We have prepared this prospectus supplement to o add the following persons to the table as holders of warrants and underlying shares of common stock: Number of Warrants and Underlying Ownership Common Stock Owned Prior to After Resale Resale of Warrants of Warrants --------------------------------------- ------------- Percentage of Number of Common Number of Percentage of Shares Stock Owned Warrants Shares of Number of Underlying Prior to Offered by Common Name and Address of Holders Warrants the Warrants Resale Holder Stock - --------------------------------------- --------- ------------ ------------- ---------- ------------- Carlyle High Yield Partners, L.P. 520 Madison Avenue, 41st Floor New York, NY 10022..................... 10,000 76,000 -- 10,000 -- Carlyle High Yield Partners II, Ltd. 520 Madison Avenue, 41st Floor New York, NY 10022..................... 3,000 22,800 -- 3,000 -- TCW Crescent/Mach I, L.P. 865 South Figueroa Street, 21st Floor Los Angeles, CA 90017.................. 2,100 15,960 -- 2,100 -- None of the above holders has a material relationship with us, except as described in the accompanying prospectus.o replace the information contained in the table with respect to the following holders: Number of Warrants and Underlying Ownership Common Stock Owned Prior to After Resale Resale of Warrants of Warrants --------------------------------------- ------------- Percentage of Number of Common Number of Percentage of Shares Stock Owned Warrants Shares of Number of Underlying Prior to Offered by Common Name and Address of Holders Warrants the Warrants Resale Holder Stock - --------------------------------------- --------- ------------ ------------- ---------- ------------- TCW Leveraged Income Investment Trust L.P. 865 South Figueroa Street, 21st Floor Los Angeles, CA 90017................... 3,150 23,940 -- 3,150 -- TCW Leveraged Income Trust II L.P. 865 South Figueroa Street, 21st Floor Los Angeles, CA 90017................... 3,150 23,940 -- 3,150 -- TCW Crescent Mezzanine Partners II, L.P. 865 South Figueroa Street, 21st Floor Los Angeles, CA 90017................... 27,044 205,534 -- 27,044 -- TCW Crescent Mezzanine Trust II 865 South Figueroa Street, 21st Floor Los Angeles, CA 90017................... 6,556 49,826 -- 6,556 -- The date of this Prospectus Supplement is January 3, 2001. 2