PROSPECTUS SUPPLEMENT 
 (TO PROSPECTUS DATED JUNE 18, 1997) 
  
               4,000,000 TRUST CONVERTIBLE PREFERRED SECURITIES 
                           MCKESSON FINANCING TRUST 
                5% TRUST CONVERTIBLE PREFERRED SECURITIES 
        (LIQUIDATION AMOUNT $50 PER CONVERTIBLE PREFERRED SECURITY) 
               GUARANTEED TO THE EXTENT SET FORTH HEREIN BY, 
                            MCKESSON CORPORATION 
                      ------------------------------    
  
      This Prospectus Supplement supplements and amends the Prospectus dated
 June 18, 1997 (the "Prospectus") relating to the 5% Trust Convertible
 Preferred Securities (the "Convertible Preferred Securities"), which
 represent preferred undivided beneficial interests in the assets of
 McKesson Financing Trust, a statutory business trust formed under the laws
 of the State of Delaware, and the shares of common stock, par value $.01
 per share, of McKesson Corporation, a Delaware corporation ("McKesson"),
 issuable upon conversion of the Convertible Preferred Securities. 
  
      McKesson and HBO & Company ("HBOC"), a leading healthcare information
 company, have signed a definitive merger agreement for McKesson to acquire
 HBOC.  Under the terms of the merger agreement, stockholders of HBOC would
 receive a fixed exchange ratio of 0.37 shares of McKesson common stock for
 each share of HBOC common stock in a tax-free exchange.  The merger of the
 two companies, which is subject to regulatory approval, McKesson and HBOC
 shareholder approval and other customary conditions, would be accounted for
 as a pooling of interests and is anticipated to close in the first quarter
 of 1999.  The new company would be named McKesson HBOC, and the corporate
 headquarters of McKesson HBOC would be located in San Francisco,
 California. 
  
      Upon completion of the merger, Charles W. McCall, currently president
 and chief executive officer of HBOC, would become chairman of McKesson
 HBOC's board of directors, and Mark A. Pulido, currently president and
 chief executive officer of McKesson, would become president and chief
 executive officer of McKesson HBOC.  Also upon completion of the merger,
 McKesson HBOC's board of directors would consist of ten members, which
 would include five members from the current McKesson board and five from
 the current HBOC board.  
  
                                                      (continued on next page)
  
 PROSPECTIVE INVESTORS SHOULD CAREFULLY CONSIDER MATTERS DISCUSSED UNDER THE
 CAPTION "RISK FACTORS" BEGINNING ON PAGE 6 OF THE PROSPECTUS. 
  
 THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES
 AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE
 SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION
 PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS.  ANY
 REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. 
  
 The date of this Prospectus Supplement is October 26, 1998.
  
      The table on pages 56 through 58 of the Prospectus, which sets forth
 information with respect to the Selling Holders (as defined in the
 Prospectus) and the respective amounts of Convertible Preferred Securities
 beneficially owned by each Selling Holder that may be offered pursuant to
 the Prospectus (as supplemented and amended), is hereby amended (i) by the
 deletion of items 1, 9, 34 and 54, respectively, of that table and the
 substitution therefor of the following: 



  
                                    Convertible Preferred                            Convertible Preferred
                                    Securities Owned         Number of               Securities Owned
                                    Prior to Offering        Convertible Preferred   After Offering  
  "Selling Holder                   Number        Percent    Securities Offered      Number        Percent   

                                                                                         
 1.  Fidelity Hastings Street 
     Trust:  Fidelity Fund (1)      206,300        5.16%         206,300                0            0.0%

 9   Fidelity Financial Trust: 
     Fidelity Convertible 
     Securities Fund (1)             26,900        0.67%          26,900                0            0.0%

 34. Fidelity Management Trust  
     Company (4)                     16,200        0.41%          16,200                0            0.0%

 54. Fidelity Advisor Series I:   
     Fidelity Advisor Growth &  
     Income Fund (1)                  3,600        0.09%           3,600                0            0.0%


 --------------------------   
  
   (1)  The entity is either an investment company or a portfolio of an
        investment company registered under Section 8 of the Investment
        Company Act of 1940, as amended, or a private investment account
        advised by Fidelity Management & Research Company ("FMR Co.").  FMR
        Co. is a Massachusetts corporation and an investment advisor
        registered under Section 203 of the Investment Advisers Act of
        1940, as amended, and provides investment advisory services to each
        of such Fidelity entities identified above, and to other registered
        investment companies and to certain other funds which are generally
        offered to a limited group of investors.  FMR Co. is a wholly-owned
        subsidiary of FMR Corp. ("FMR"), a Massachusetts corporation.  As
        of October 23, 1998, funds and accounts advised by FMR beneficially
        owned 8,693,130 shares (approximately 8.8%) of the McKesson Common
        Stock issued and outstanding. 
  
   (4)  Shares indicated as owned by such entity are owned directly by
        various private investment accounts, primarily employee benefit
        plans for which Fidelity Management Trust Company ("FMTC") serves
        as trustee or managing agent.  FMTC is a wholly-owned subsidiary of
        FMR and a bank as defined in Section 3(a)(6) of the Securities
        Exchange Act of 1934, as amended." 
  
      The Prospectus, together with this Prospectus Supplement, constitutes
 the prospectus required to be delivered by Section 5(b) of the Securities
 Act of 1933, as amended, with respect to offers and sales of the
 Convertible Preferred Securities and McKesson Common Stock issuable upon
 conversion of the Convertible Preferred Securities. All references in the
 Prospectus to "this Prospectus" are hereby amended to read "this
 Prospectus (as supplemented and amended)".