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 The GAMCO Growth Fund (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 The GAMCO Growth
Fund (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