POWER OF ATTORNEY



     Know all by these presents, that the undersigned hereby

constitutes and appoints each of Kristina Veaco, Donna Spinola and

Ivan D. Meyerson, signing singly, the undersigned's true and lawful

attorneys-in-fact to:



   (1)  execute for and on behalf of the undersigned, in the

        undersigned's capacity as an officer and/or director of

        McKesson Corporation (the "Company"), Forms 3, 4 and 5 in

        accordance with Section 16(a) of the Securities Exchange Act

        of 1934 and the rules thereunder, which execution may include

        the insertion of the undersigned's typed name on the signature

        line of such Forms; and



   (2)  do and perform any and all acts for and on behalf of the

        undersigned which may be necessary or desirable to complete

        and execute any such Form 3, 4 or 5 and timely file such form

        with the United States Securities and Exchange Commission and

        any stock exchange or similar authority; and



   (3)  take any other action of any type whatsoever in connection with

        the foregoing which, in the opinion of such attorney-in-fact,

        may be of benefit to, in the best interest of, or legally

        required by, the undersigned, it being understood that the

        documents executed by such attorney-in-fact on behalf of the

        undersigned pursuant to this Power of Attorney shall be in such

        form and shall contain such terms and conditions as such

        attorney-in-fact may approve in such attorney-in-fact's

        discretion.



     The undersigned hereby grants to each such attorney-in-fact full

power and authority to do and perform any and every act and thing

whatsoever requisite, necessary or proper to be done in the exercise

of any of the rights and powers herein granted, as fully to all

intents and purposes as the undersigned might or could do if personally

present, with full power of substitution or revocation, hereby

ratifying and confirming all that such attorney-in-fact, or such

attorney-in-fact's substitute or substitutes, shall lawfully do or

cause to be done by virtue of this power of attorney and the rights

and powers herein granted.  The undersigned acknowledges that the

foregoing attorneys-in-fact, in serving in such capacity at the

request of the undersigned, are not assuming, nor is the Company

assuming, any of the undersigned's responsibilities to comply with

Section 16 of the Securities Exchange Act of 1934.



     This Power of Attorney shall remain in full force and effect

until the undersigned is no longer required to file Forms 3, 4 and 5

with respect to the undersigned's holdings of and transactions in

securities issued by the Company, unless earlier revoked by the

undersigned in signed writing delivered to the foregoing

attorneys-in-fact.



  IN WITNESS WHEREOF, the undersigned has caused this

Power of Attorney to be executed as of this 28th day of January, 2004.



/s/ Randall N. Spratt

Signature



Randall N. Spratt

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