Exhibit 16.1 ARTHUR ANDERSEN LLP 105 Eisenhower Parkway Roseland, NJ 07068-1099 973-403-6100 www.andersen.com Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 May 6, 2002 Dear Sir/Madam: We have read the second, third, fourth and fifth paragraphs of Item 4 included in the Form 8-K dated May 1, 2002 of Pharmaceutical Resources, Inc. to be 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