Eighty-five patients with accelerated (preinfarction) angina are reported. Six suffered acute myocardial infarction awaiting catheterization and coronary angiography, so were not studied. Seventy-nine had coronary arteriography and other angiographic and hemodynamic studies. Fifteen of these 79 patients had normal coronary arteriograms; 64 had significant coronary artery obstruction. The clinical manifestations in 64 abnormal patients did not differ from those with normal arteriograms. Hemodynamic abnormalities correlated with the severity of arteriographic abnormalities. Of 70 patients with coronary artery disease, including the six not studied because of infarction, 48 were treated surgically with a mortality of 12.5%. Mortality for those 22 patients treated without surgery was 27%. Mortality could be correlated with certain risk factors: (1) congestive heart failure; (2) more than three-vessel coronary disease; (3) left ventricular end-diastolic pressure > 12 mm Hg; (4) cardiac index <2.7 liters/min/m2; (5) stroke index <35 ml/beat/m2; (6) estimated cardiac work (mean aortic pressure × cardiac index) <240 units; and (7) ejection fraction <0.50. Cardiac catheterization and angiography were performed without major complications in 97% of patients.