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 500,000 shares of the Company's Common stock, par value $0.01 per share,
issuable pursuant to the 1998 Canadian Stock Incentive 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 Canadian Stock
Incentive 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