Exhibit 99.906CERT Certification Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsection (a) and (b) of section 1350, chapter 63 of title 18, United States Code) In connection with the attached Report of Allmerica Securities Trust (the "Trust") on Form N-CSR to be filed with the Securities and Exchange Commission for the period ended December 31, 2004 (the "Report"), each of the undersigned officers of the Trust does hereby certify that, to the best of such officer's 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 Trust as of, and for, the periods presented in the Report. Dated: February 24, 2005 /s/ John P. Kavanaugh - ---------------------------------------- John P. Kavanaugh President and Chairman Dated: February 24, 2005 /s/ Paul T. Kane - ---------------------------------------- Paul T. Kane Assistant Vice President and Treasurer (Principal Accounting Officer and Principal Financial Officer)