EXHIBIT 32.2 CERTIFICATE OF THE PRINCIPAL FINANCIAL OFFICER OF DIOMED HOLDINGS, INC. (REGISTRANT) PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 I, David B. Swank, Chief Financial Officer of the Registrant, certify to the best of my knowledge and belief pursuant to Section 906 of Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350) that: (1) The Quarterly Report on Form 10-QSB for the period ended June 30, 2004, which this statement accompanies, fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and (2) The information contained in the Quarterly Report on Form 10-QSB fairly presents, in all material respects, the financial condition and result of operations of the Registrant. Date: August 12, 2004 /s/ DAVID B. SWANK -------------------------- David B. Swank Chief Financial Officer (Principal Financial Officer)