A patient had total occlusion of the left main coronary artery that was proved by coronary arteriography. The patient was initially seen with clinical signs of congestive heart failure but without symptoms of angina pectoris or ECG evidence of myocardial infarction. The patient's extensive right-to-left coronary artery collaterals may have contributed to the absence of chest pain. Because of the severe left ventricular dysfunction and the absence of chest pain, the patient was treated with medical therapy. Six months after the cardiac catheterization, he was alive and well under New York Heart Association functional classification II.