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 Quarterly Report of Anworth Mortgage Asset Corporation (the "Company") on Form 10-Q for the quarterly period ended September 30, 2002, as filed with the Securities and Exchange Commission on November 14, 2002 (the "Report"), I, Joseph Lloyd McAdams, Chairman of the Board, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that: 1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. By: /s/ Joseph Lloyd McAdams -------------------------------------- Joseph Lloyd McAdams Chairman of the Board, President and Chief Executive Officer November 14, 2002