EXHIBIT 16 LETTER REGARDING CHANGE IN CERTIFYING ACCOUNTANT - -------------------------------------------------------------------------------- [Ernst & Young, LLP Letterhead] Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 We have read Item 4 of Form 8-K dated May 9, 2000, of CNB Financial Corporation and are in agreement with the statements contained in the paragraphs on page 2 therein. We have no basis to agree or disagree with other statements of the registrant contained therein. /s/Ernst & Young, LLP - ------------------------------------ May 16, 2000 Pittsburgh, Pennsylvania