A kindred with a high incidence of cardiac disease has been described. The mode of transmission is probably on the basis of a sex limited autosomal dominant gene. Postmortem examination in Case 1 showed coronary atherosclerosis with occlusion of the anterior descending branch of the left coronary artery. Three members of this family had complete heart block with Adams-Stokes attacks requiring implantation of an artificial pacemaker. Two asymptomatic children had first degree atrioventricular block. Other manifestations of cardiac disease include cardiomegaly, intraventricular conduction disturbances, myocardial infarction, and primary T wave changes. Certain evidence favors the interpretation that the etiology of heart disease is an unspecified cardiomyopathy; however, because of the presence of atherosclerosis in the one necropsied case and of myocardial infarction in two others, ischemic heart disease cannot be excluded.