It is not unusual for patients with arteriosclerotic heart disease and angina pectoris to have an apical late-systolic heart murmur secondary to papillary muscle dysfunction.1 Patients with hypertrophic muscular subaortic stenosis also have angina-like pains,2 an apical systolic murmur resembling that of mitral regurgitation,3 and an electrocardiogram which suggests myocardial infarction.4 These two different afflictions, coronary artery disease and hypertrophic muscular subaortic stenosis, may well mimic each other and be difficult to separate clinically. Therefore, one might expect to find individuals being treated for arteriosclerotic heart disease, who in reality have hypertrophic muscular subaortic stenosis. Two such patients are reported. Patient Summaries Patient 1. —A 41-year-old white man was given a medical discharge from the Armed Forces in July 1964 at the age of 39 for arteriosclerotic heart disease with angina pectoris and mitral insufficiency. At that time, he had had a heart murmur for at