MCKESSON CORPORATION
                                                                    EXHIBIT 99.2

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
      AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the quarterly report of McKesson Corporation (the "Company")
on Form 10-Q for the period ended September 30, 2002 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, William
R. Graber, Chief Financial Officer of the Company certify, pursuant to 18 U.S.C.
Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of
2002, that to the best of my knowledge:

(1)      The Report fully complies with the  requirements  of section 13(a) or
         15(d) of the Securities Act of 1934; and

(2)      The  information  contained  in the Report  fairly  presents,  in all
         material respects, the financial condition and results of operations of
         the Company

 /s/ William R. Graber
- ------------------------------------
WILLIAM R. GRABER
Chief Financial Officer
November 12, 2002

This certification accompanies the Report pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, and shall not, except to the extent required by the
Sarbanes-Oxley Act of 2002, be deemed filed by the Company for the purposes of
Section 18 of the Securities Exchange Act of 1934, as amended.