EXHIBIT 99.1 Grant Thornton Accountants and Business Advisors April 27, 2005 U.S. Securities and Exchange Commission Office of the Chief Accountant 450 Fifth Street, NW Washington, DC 20549 Re: Xybernaut Corporation File No. 0-15086 Dear Sir or Madam: We have read Item 4.02 of Form 8-K of Xybernaut Corporation dated April 5, 2005 and agree with the statements concerning our Firm contained therein. Very truly yours, /s/ Grant Thornton LLP Suite 300 2070 Chain Bridge Road Vienna, VA 22182-2536 T 703.847.7500 F 703.848.9580 W www.grantthornton.com Grant Thornton LLP US Member of Grant Thornton International