EXHIBIT 16 March 16, 2000 Securities and Exchange Commission Washington, D.C. 20549 Re: United Diagnostic, Inc. File No. 0-11772 Dear Sir or Madam: We have read Item 4 of the Form 8-K/A of United Diagnostic, Inc. dated March 16, 2000, and agree with the statements contained therein regarding our firm. Very truly yours, Grant Thornton LLP