EXHIBIT 99.1

                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,
                       AS ADOPTED PURSUANT TO SECTION 906
                        OF THE SARBANES-OXLEY ACT OF 2002

     In connection with the Annual Report of Chesapeake Energy Corporation (the
"Company") on Form 10-K for the year ended December 31, 2002 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Aubrey
K. McClendon, Chairman and Chief Executive Officer of the Company, certify,
pursuant to 18 U.S.C (S) 1350, as adopted pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

     1.   The Report fully complies with the requirements of Section 13(a) or
          15(d) of the Securities Exchange Act of 1934; and

     2.   The information contained in the Report fairly presents, in all
          material respects, the financial condition and results of operations
          of the Company.


                                            /s/ AUBREY K. MCCLENDON
                                            -----------------------
                                            Aubrey K. McClendon
                                            Chairman and Chief Executive Officer

Date: February 26, 2003