Ten patients with acute myocarditis, who were initially seen with clinical signs of acute myocardial infarction, will be discussed. All had symptoms and seven had laboratory evidence of an acute viral infection. Acute cardiac findings consisted of chest pain in nine patients, compatible ECGs and elevated creatine kinase levels in 10, positive MB fractions in eight, and regional wall motion abnormalities in eight. Acutely, the left ventricular ejection fraction was less than 55% in six patients; ventricular ectopy occurred in five patients, bundle branch block in four, transient junctional escape rhythm in three, and congestive heart failure in three. Among the nine patients followed-up for 1 to 14 months there was one death, five patients had normal results of exercise tests, and three had normal coronary angiograms. Wall motion abnormalities persisted in four patients; ejection fraction improved in five and was less than 55% in three. These findings suggest that focal myocardial damage may occur during acute viral myocarditis and mimic acute myocardial infarction resulting from atherosclerotic coronary artery disease.