Exhibit 99.4

September 14, 2004

Board of Directors
Inveresk Research Group, Inc.
11000 Weston Parkway
Cary, NC 27513


Re: Amendment No. 1 to the Registration Statement on Form S-4 of
    Charles River Laboratories International, Inc. (File No. 333-118257)

Ladies and Gentlemen:

Reference is made to our opinion letter, dated June 30, 2004, with respect to
the fairness from a financial point of view to the holders of the outstanding
shares of common stock, par value $0.01 per share, of Inveresk Research
Group, Inc. (the "Company") of the Consideration (as defined in the opinion)
to be received by such holders, taken in the aggregate, pursuant to the
Agreement and Plan of Merger, dated as of June 30, 2004, among Charles River
Laboratories International, Inc. ("Charles River"), Indigo Merger I Corp., a
wholly owned subsidiary of Charles River, Indigo Merger II Corp., a wholly
owned subsidiary of Charles River, and the Company.

The foregoing opinion letter is provided for the information and assistance
of the Board of Directors of the Company in connection with its consideration
of the transaction contemplated therein and is not to be used, circulated,
quoted or otherwise referred to for any other purpose, nor is it to be filed
with, included in or referred to in whole or in part in any registration
statement, proxy statement or any other document, except in accordance with
our prior written consent. We understand that the Company has determined to
include our opinion in the above-referenced Registration Statement.

In that regard, we hereby consent to the reference to our opinion under the
captions "SUMMARY--Opinion of Inveresk's Financial Advisor," "THE
TRANSACTION--Background of the Transaction," "THE TRANSACTION--Inveresk
Reasons for the Transaction; Recommendation of the Inveresk Board of
Directors" and "OPINION OF INVERESK'S FINANCIAL ADVISOR" and to the inclusion
of the foregoing opinion in the Proxy Statement/Prospectus included in the
above-mentioned Registration Statement. In giving such consent, we do not
thereby admit that we come within the category of persons whose consent is
required under Section 7 of the Securities Act of 1933 or the rules and
regulations of the Securities and Exchange Commission thereunder.

Very truly yours,


/s/ Goldman, Sachs & Co.
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(GOLDMAN, SACHS & CO.)