107 patients suffering from angina at rest associated with ST segment changes underwent coronary arteriography. 46 patients showed ST segment elevation during ischemic attacks (group I) while 61 patients exhibited ST segment depression during chest pain (group II). Non-significant coronary artery disease was more frequent in group I patients (group I 15%, group II 5%) as well as one vessel disease (group I 33%, group II 15%) while multivessel disease and left main involvement were more frequent in group II patients (group I 28%, group II 60%). Depression of left ventricular function was found in similar percentage of cases in both groups. During hospitalization all patients were treated with calcium antagonists (Nifedipine 10/20 mg every six hours) and/or nitrates (2% nitroglycerin ointment 2 inches every six/four hours) with one death (occurring after coronary arteriography) and eleven non-fatal myocardial infarctions. 50 patients underwent coronary bypass grafting with four perioperative deaths and six nonfatal myocardial infarctions. Most of the surgically treated patients were poorly responsive to medical treatment and had multivessel disease or left main involvement. Since these features are known to be related to a poor prognosis with medical treatment, surgical results in such patients seem satisfactory.