Ten patients with angina pectoris underwent multistage maximal treadmill exercise with hemodynamic measurements before, and again 6 months following coronary artery surgery. Subjectively, 9 patients experienced a total and one patient partial relief from angina, and all patients noted improved exercise tolerance following surgery. Objectively, significant improvement was found in duration of exercise, maximal oxygen intake in maximal cardiac output, maximal heart rate, and maximal pressure-rate product. Surgery did not significantly affect systemic or pulmonary arterial pressures during exercise. Despite these improvements, maximal cardiac output did not return to normal levels following surgery, due to an unexpected but significant reduction in stroke volume.