As filed with the Securities and Exchange Commission on October 18, 1999
Registration No. 333-66359

--------------------------

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1
to
FORM S-3
REGISTRATION STATEMENT
under
the Securities Act of 1933

McKESSON HBOC, INC. Delaware 94-3207296
(Exact name of Registrant (State or other jurisdiction of (I.R.S. employer
as specified in its charter) incorporation or organization) identification number)

McKesson Plaza
One Post Street
San Francisco, California 94104
(415) 983-8300
(Address, including zip code, and telephone number, including area code, of
Registrant's principal executive offices)

Ivan D. Meyerson
Senior Vice President, General Counsel and Corporate Secretary
McKesson HBOC, Inc.
McKesson Plaza, One Post Street
San Francisco, California 94104
(415) 983-8300
(Name, address, including zip code, and telephone number,
including area code, of agent for service)
--------------------
Copy to:
Gregg A. Noel
Skadden, Arps, Slate, Meagher & Flom LLP
300 South Grand Avenue, Suite 3400
Los Angeles, California 90071
(213) 687-5000

Approximate date of commencement of proposed sale to the public:
From time to time after this registration statement becomes effective.

--------------------
If the only securities being registered on this form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [ ]

If any of the securities being registered on this form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities being offered only in connection with dividend or
interest reinvestment plans, please check the following box. [ ]

If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [ ]

If this form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [ ]

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [ ]

DEREGISTRATION OF SECURITIES

The purpose of this Post-Effective Amendment No. 1 to this Registration
Statement is to deregister all shares of common stock, par value $.01 per share
of McKesson HBOC, Inc., a Delaware corporation (previously named McKesson
Corporation) which have not been sold pursuant to this Registration Statement.

The Securities and Exchange Commission declared this Registration Statement
effective on November 20, 1998. This Registration Statement was filed in
accordance with a registration rights agreement, dated as of June 22, 1998 (the
"Registration Rights Agreement"), by and among McKesson HBOC, Inc. and the
parties named therein. In the Registration Rights Agreement, McKesson HBOC,
Inc. agreed to use its reasonable best efforts to keep the Registration
Statement effective for at least 120 days. This Post-Effective Amendment No. 1
is being filed in accordance with McKesson HBOC, Inc.'s undertaking set forth in
Part II, Item 17(a)(3) of this Registration Statement.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 16. List of Exhibits.

Exhibit Number Description
- - -------------- -----------

24.1* Power of Attorney, dated as of May 29, 1998.

24.2** Power of Attorney, dated as of April 27, 1999.

24.3** Power of Attorney, dated as of October 12, 1999.

________

* Previously filed
** Filed herewith

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the
Company certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form S-3 and has duly caused this Post-Effective
Amendment to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Francisco, State of California, on the 18th day
of October, 1999.

McKesson HBOC, Inc.

By: /s/ Ivan D. Meyerson
----------------------------------------------
Name: Ivan D. Meyerson
Title: Senior Vice President, General
Counsel and Corporate Secretary

Pursuant to the requirements of the Securities Act of 1933, as amended,
this Amendment has been signed below by the following persons in the capacities
and on the date indicated.

Signature Title
--------- -----

* Co-President and
- - --------------------------------- Co-Chief Executive Officer and Director
John H. Hammergren (principal executive officer)

* Co-President and
- - --------------------------------- Co-Chief Executive Officer and Director
David L. Mahoney (principal executive officer)

* Senior Vice President and Controller and
- - --------------------------------- Acting Chief Financial Officer
Heidi E. Yodowitz (principal financial and accounting officer)

*
- - --------------------------------- Director
Alfred C. Eckert III

*
- - --------------------------------- Director
Tully M. Friedman

*
- - --------------------------------- Director
Alton F. Irby III

Signature Title
--------- -----

*
- - --------------------------------- Director
M. Christine Jacobs

*
- - --------------------------------- Director
Gerald E. Mayo

*
- - --------------------------------- Director
Charles W. McCall

*
- - --------------------------------- Director
James V. Napier

*
- - --------------------------------- Director
David S. Pottruck

*
- - --------------------------------- Director
Carl E. Reichardt

* Chairman of the Board and
- - --------------------------------- Director
Alan Seelenfreund

*
- - --------------------------------- Director
Jane E. Shaw

*By: /s/ Ivan D. Meyerson
-----------------------------
Ivan D. Meyerson
Attorney-in-fact

Dated: October 18, 1999

EXHIBIT INDEX

Exhibit Number Description
- - -------------- -----------

24.2 Power of Attorney, dated as of April 27, 1999

24.3 Power of Attorney, dated as of October 12, 1999