EXHIBIT 16 May 9, 2002 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 Dear Sir/Madam: We have read the first four paragraphs of Item 4 included in the Form 8-K dated May 9, 2002 of Cardinal Health, Inc. and subsidiaries filed with the Securities and Exchange Commission and are in agreement with the statements contained therein. Very truly yours, /s/ ARTHUR ANDERSEN LLP Arthur Andersen LLP