EXHIBIT 16.1 June 25, 2001 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 Dear Sir/Madam: We have read the two paragraphs of Item 4 included in the Form 8-K dated June 21, 2001 of Concentra Operating Corporation filed with the Securities and Exchange Commission and are in agreement with the statements contained therein. Very truly yours, /s/ Arthur Andersen LLP - ----------------------- Arthur Andersen LLP