Exhibit 32.1 CERTIFICATION PURSUANT TO U.S.C. SECTION 1350 AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 I, Raymond C. Kubacki, Jr., President and Chief Executive Officer of Psychemedics Corporation (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: (1) The Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2004, as filed with the Securities and Exchange Commission on May 12, 2004 (the "Report"), 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 Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Date: May 12, 2004 By: /s/ Raymond C. Kubacki, Jr. -------------------------------- Raymond C. Kubacki, Jr. Chairman and Chief Executive Officer 21