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EXHIBIT 24



                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS THAT the undersigned directors and
officers of McKesson Corporation, a Delaware corporation (the "Company") do
hereby constitute and appoint Ivan D. Meyerson and Kristina Veaco his or her
true and lawful attorney and agent, each with full power and authority (acting
alone and without the other) to execute in the name and on behalf of the
undersigned as such Director and/or Officer, a Registration Statement on Form
S-8 under the Securities Act of 1933, as amended, with respect to the
registration of shares of the Company's Common Stock, par value $.01 per share,
that may be issued by the Company under the McKesson Corporation 1999 Stock
Option and Restricted Stock Plan, and to execute any and all amendments to such
Registration Statement, whether filed prior or subsequent to the time such
Registration Statement becomes effective. The undersigned hereby grants unto
such attorneys and agents, and each of them, full power of substitution and
revocation in the premises and hereby ratifies and confirms all that such
attorneys and agents may do or cause to be done by virtue of these presents.

/s/ ALAN SEELENFREUND
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Alan Seelenfreund
Chairman of the Board

/s/ JOHN H. HAMMERGREN
--------------------------------------------------
John H. Hammergren
President and Chief Executive Officer and Director

/s/ NIGEL REES
--------------------------------------------------
Nigel Rees
Vice President and Controller

/s/ WILLIAM R. GRABER
--------------------------------------------------
William R. Graber
Senior Vice President and Chief Financial Officer

/s/ ALFRED C. ECKERT III
--------------------------------------------------
Alfred C. Eckert III
Director

/s/ TULLY M. FRIEDMAN
--------------------------------------------------
Tully M. Friedman
Director

/s/ M. CHRISTINE JACOBS
--------------------------------------------------
M. Christine Jacobs
Director

/s/ MARTIN M. KOFFEL
--------------------------------------------------
Martin M. Koffel
Director

/s/ GERALD E. MAYO
--------------------------------------------------
Gerald E. Mayo
Director

/s/ JAMES V. NAPIER
--------------------------------------------------
James V. Napier
Director

/s/ CARL E. REICHARDT
--------------------------------------------------
Carl E. Reichardt
Director

/s/ JANE E. SHAW
--------------------------------------------------
Jane E. Shaw
Director


Dated: August 13, 2001