EXHIBIT 23.3 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of McKesson Corporation of our reports dated February 6, 1998, with respect to the consolidated financial statements of HBO & Company as of December 31, 1997 and 1996 and for each of the three years in the period ended December 31, 1997, included in the Form 8-K/A of McKesson Corporation, and to all references to our Firm, included in this Registration Statement. ARTHUR ANDERSEN LLP Atlanta, Georgia October 29, 1998