EXHIBIT 32.1

                    CERTIFICATION OF CHIEF EXECUTIVE OFFICER
                         CALLISTO PHARMACEUTICALS, INC.
                FORM 10-K/A FOR THE YEAR ENDED DECEMBER 31, 2004
                 PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED
            PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I am the Chief Executive Officer of Callisto  Pharmaceuticals,  Inc., a Delaware
corporation (the "Company"). I am delivering this certificate in connection with
the Form 10-K/A of the Company  for the year ended  December  31, 2004 and filed
with the Securities and Exchange Commission ("Form 10-K/A").

Pursuant to 18 U.S.C.  Section 1350,  as adopted  pursuant to Section 906 of the
Sarbanes-Oxley  Act of 2002, I hereby certify that, to the best of my knowledge,
the Form 10-K/A fully complies with the requirements of Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 and that the information  contained
in the Form 10-K/A  fairly  presents,  in all material  respects,  the financial
condition and results of operations of the Company.

Date: June 6, 2005
                                        /s/ Gary S. Jacob
                                        ------------------------
                                        Gary S. Jacob
                                        Chief Executive Officer