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 11,700,000 shares of the Company's Common stock, and options to purchase
shares of the Company's Common stock, par value $0.01 per share, issuable
pursuant to the McKesson HBOC, Inc. 1999 Stock Option and Restricted Stock Plan
(the "1999 Plan").  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 1999 Plan, 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