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

I, Henry G. Van der Eb, Chief  Executive  Officer of The GAMCO Mathers 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 14, 2007            /s/ Henry G. Van der Eb
     ----------------------         --------------------------------------------
                                    Henry G. Van der Eb, Chief Executive Officer



I, Agnes Mullady,  Principal  Financial Officer & Treasurer of The GAMCO Mathers
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
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                                    Agnes Mullady, Principal Financial Officer
                                    & Treasurer