Exhibit 99.1

                   CERTIFICATION OF PERIODIC FINANCIAL REPORTS

I, David W. Dorman, Chief Executive Officer of AT&T Corp., certify, pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1)      the Annual Report on Form 10-K for the fiscal year ended December 31,
         2002 (the "Periodic Report") which this statement accompanies fully
         complies with the requirements of Section 13(a) or 15(d) of the
         Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)) and

(2)      information contained in the Periodic Report fairly presents, in all
         material respects, the financial condition and results of operations of
         AT&T Corp.

Dated: March 28, 2003

                                                  /s/ David W. Dorman
                                                  ------------------------------
                                                  David W. Dorman