Exhibit 10.21 FOURTH AMENDMENT TO REVOLVING LOAN AGREEMENT BETWEEN AMSOUTH BANK AND SURGICAL LASER TECHNOLOGIES DATED MAY 31, 2000 RESOLVED, that effective January 1, 2003, AmSouth Bank and Surgical Laser Technologies, Inc. hereby declare and certify by the signatures indicated below, that Article V, Section 5.14 shall be added to the Loan Agreement dated May 31, 2000, and as amended pursuant to a First Amendment dated as of February 20, 2002, by a Second Amendment dated as of June 27, 2002, and by a Third Amendment dated as of February 27, 2003, to read as follows: "5.14. GUARANTY OF PARENT COMPANY. The Borrower shall cause its parent company, PhotoMedex, Inc., to guarantee, in an instrument in a form reasonably equivalent to the guaranty attached hereto, the Borrower's performance under this Loan Agreement." Accepted and Agreed as of this 27th day of February, 2003. AmSouth Bank Surgical Laser Technologies, Inc. By: /s/ Rhett D. Jordan By:/s/ Jeffrey O'Donnell Rhett D. Jordan Jeffrey O'Donnell Its Vice President Its President and CEO By: /s/ Dennis McGrath Dennis McGrath Its Chief Financial Officer In assent herewith: PhotoMedex, Inc. By /s/ Jeffrey O'Donnell Jeffrey O'Donnell Its President and CEO By: /s/ Dennis McGrath Dennis McGrath Its Chief Financial Officer