EXHIBIT 32.1

CERTIFICATION PURSUANT TO
18 U.S.C. § 1350, AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

     Pursuant to 18 U.S.C. Section 1350, I, the undersigned Chief Executive Officer of Vion Pharmaceuticals, Inc. (the ‘‘Company’’), hereby certify that the Quarterly Report on Form 10-Q of the Company for the quarter ended September 30, 2008 (the ‘‘Report’’) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: November 6, 2008

/s/ Alan Kessman  

Alan Kessman 

Chief Executive Officer 

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to Vion Pharmaceuticals, Inc. and will be retained by Vion Pharmaceuticals, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.