1 EXHIBIT 21 SUBSIDIARIES OF THE REGISTRANT There is no parent of the Company. The following is a listing of the significant subsidiaries of the Company, or if indented, subsidiaries of the Company under which they are listed: JURISDICTION OF ORGANIZATION --------------- HBO & Company............................................... Delaware McKesson Canada Inc......................................... Canada Medis Health and Pharmaceutical Services Inc.............. Canada GM Holdings, Inc............................................ Delaware McKesson General Medical Corp............................. Virginia