EXHIBIT 23.3 [LETTERHEAD OF BEAR, STEARNS & CO. INC.] November 9, 1998 Board of Directors McKesson Corporation McKesson Plaza One Post Street San Francisco, California 94104 Ladies and Gentlemen: We hereby consent to the inclusion in the Registration Statement on Form S-4 (the "Registration Statement") of McKesson Corporation, a Delaware corporation ("McKesson"), of our opinion letter appearing as Annex D to the Joint Proxy Statement/Prospectus which is a part of the Registration Statement and to the references to our firm name in the 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, as amended (the "Securities Act"), or the rules and regulations of the Securities and Exchange Commission (the "SEC") promulgated thereunder, nor do we admit that we are experts with respect to any part of the Registration Statement within the meaning of the term "experts" as used in the Securities Act, or the rules and regulations of the SEC promulgated thereunder. Very truly yours, Bear, Stearns & Co. Inc. By: /s/ Kevin P. Clarke ------------------------- Name: Kevin P. Clarke Title: Senior Managing Director