<Page> EXHIBIT 16.1 May 20, 2002 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 second sentence of the first paragraph of Item 4 and the second through fourth paragraphs of Item 4 included in the Form 8-K/A dated May 8, 2002 of Bio Technology General Corp. 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 cc: Mr. John Bond Senior Vice President - Finance, Bio-Technology General Corp.