Variant angina pectoris, usually not precipitated by exertion or emotional stress, often is more severe and lasts longer than classic angina. The pain tends to recur at about the same time each day. Arrhythmias, usually ventricular, occur in about 50% of cases during the peak of pain. Electrocardiograms show a characteristic ST segment elevation during pain, which is in contrast to the ST segment depression of classic angina pectoris. Pain may be due, at least in some cases, to a temporary increase in tonus of a single, large, narrowed coronary artery. Chemical changes in the myocardium and plasma catecholamine changes differ from those occurring in classic angina pectoris. The course of the disease is highly variable but the prognosis must be regarded as grave, since single large vessel disease, present in most cases, is associated with severe myocardial ischemia. Patients with variant angina pectoris should be studied early with coronary arteriography and considered for coronary artery bypass surgery if appropriate.