Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C. SS.1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 In connection with the Annual Report of MedSource Technologies, Inc., (The "Company") on Form 10-K for the period ended June 30, 2003, as filed with the Securities and Exchange Commission on the date hereof (the "Report"), I William J. Kullback, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 that, to the best of my knowledge: 1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities and Exchange Act of 1934; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. A signed original of this written statement required by Section 906 has been provided to the Company and furnished to the Securities and Exchange Commission or its staff upon request. Dated: September 26, 2003 /s/ William J. Kullback ---------------------------------------- William J. Kullback Senior Vice President - Finance and Chief Financial Officer