EXHIBIT 5.1

                                    February 10, 2000



McKesson HBOC, Inc.
McKesson Plaza
One Post Street
San Francisco, CA 94104



     I am Senior Vice President, General Counsel and Secretary of McKesson HBOC,
Inc., a Delaware corporation (the "Company").  In that capacity I have reviewed
the Registration Statement on Form S-8 to be filed by the Company with the
Securities and Exchange Commission under the Securities Act of 1933 with respect
to $50,000,000 of General Obligations under the McKesson HBOC, Inc. Deferred
Compensation Administration Plan II.  As General Counsel, I am familiar with the
Company's Restated Certificate of Incorporation and its Restated By-Laws, as
amended to date.  I have also examined such other documents, corporate records
and instruments as I have deemed necessary or appropriate for the purpose of
this opinion.

     Based upon the foregoing, I am of the opinion that the additional General
Obligations of the Company described above, will be duly authorized, validly
issued, fully paid and nonassessable.

     I hereby consent to the filing of this opinion with the Securities and
Exchange Commission as Exhibit 5.1 to the Registration Statement.

                                    Very truly yours,



                                    /s/Ivan D. Meyerson
                                    Ivan D. Meyerson
                                    Senior Vice President,
                                    General Counsel and Corporate Secretary