EXHIBIT 5


                                            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 9,875,000 shares of the Company's Common stock, par value $0.01 per share,
issuable pursuant to the McKesson HBOC, Inc. Outside Plans.  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 shares of Common
Stock of the Company, when issued in accordance with the Outside Plans, will be
legally issued, fully paid and nonassessable.

     I hereby consent to the filing of this opinion with the Securities and
Exchange Commission as Exhibit 5 to the Registration Statement.

                                       Very truly yours,



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