Appeal from a decision of the Workmen’s Compensa*990tion Board, filed July 24, 1975, which found that the claimant sustained a work-related heart attack and awarded him benefits. The sole issue raised by the appellants in their appeal to the board was the credibility of the claimant’s testimony that he had been engaged in lifting and moving several cartons immediately before and at the time he sustained a myocardial infarction. The record contains no documentary or conclusive eyewitness evidence which is of such a nature as to render the claimant’s testimony as to lifting cartons incredible as a matter of law. It is well established that issues of credibility are within the sole province of the board. Therefore, the appeal has no merit. Decision affirmed, with costs to the Workmen’s Compensation Board. Koreman, P. J., Sweeney, Kane, Main and Herlihy, JJ., concur.