[LETTERHEAD] EXHIBIT 16 April 5, 2000 Securities and Exchange Commission Mail Stop 11-3 450 5th Street, N.W. Washington, D.C. 20549 Dear Sirs/Madams: We have read and agree with the comments in Item 4 of Form 8-K of Cymer, Inc. dated April 5, 2000. Yours truly, /s/Deloitte & Touche LLP