Programmed cell death or apoptosis plays a major role in the modification of morphologic and functional maturity in various normal organ systems. However, it is also related to certain diseases. We conducted a pathological study of the apoptosis of cardiomyocytes in six cases with myocarditis (three of acute myocarditis and three of chronic or persistent myocarditis) using histochemical methods. In normal hearts obtained from autopsy cases, apoptosis was seen in endocardial cells. There was no apoptosis in myocardial cells, except for a few in myocytes with two nuclei. In myocarditis, although the myocytes of all cases with acute myocarditis did not show apoptosis, one of the three cases with chronic or persistent myocarditis showed many apoptotic myocytes. Apoptosis may be one of the mechanisms causing myocyte damage in myocarditis.