EXHIBIT 23(A) CONSENT OF INDEPENDENT AUDITORS We consent to the incorporation by reference in the Registration Statement on Form S-8 pertaining to the Syncor International Corporation Employees' Savings and Stock Ownership Plan, as Amended and Restated, of our report dated August 6, 2002, with respect to the consolidated financial statements and schedule of Cardinal Health, Inc. included in its Annual Report (Form 10-K) for the year ended June 30, 2002, filed with the Securities and Exchange Commission. The consolidated financial statements and financial statement schedule of Cardinal Health, Inc. for the years ended June 30, 2001 and 2000, were audited by auditors who have ceased operations. Those auditors expressed an unqualified opinion on those statements in their report dated July 27, 2001. /s/ Ernst & Young LLP Columbus, Ohio January 3, 2003