CERTIFICATION PURSUANT TO RULE 30A-2(B) UNDER THE 1940 ACT AND
                     SECTION 906 OF THE SARBANES-OXLEY ACT

I, Bruce N. Alpert,  Principal  Executive  Officer of GAMCO Global Series Funds,
Inc. (the "Registrant"), certify that:

         1.     The Form N-CSR of the Registrant  (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 Registrant.


Date:    August 31, 2007            /s/ Bruce N. Alpert
     ----------------------         --------------------------------------------
                                    Bruce N. Alpert, Principal Executive Officer



I, Agnes Mullady, Principal Financial Officer & Treasurer of GAMCO Global Series
Funds, Inc. (the "Registrant"), certify that:

         1.     The Form N-CSR of the Registrant  (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 Registrant.


Date:    August 31, 2007            /s/ Agnes Mullady
     ----------------------         ------------------------------------------
                                    Agnes Mullady, Principal Financial Officer
                                    & Treasurer