The results in 80 patients undergoing simultaneous aortic valve replacement and aorta-coronary saphenous vein bypass grafting were analyzed to assess the effect of operative technique. The over-all operative mortality rate of 6.3% (five of 80) did not differ significantly from our results with aortic valve replacement alone. All patients who had isolated aortic valve replacement were operated upon with moderate hypothermia. The combined operation was performed in two ways. Thirty-one patients had aortic valve replacement prior to bypass grafting with intermittent coronary ostila perfusion. There were two deaths (6.5%), and five myocardial infarctions (16.1%) were diagnosed by standard electrocardiographic and enzyme criteria. More recently, 49 patients have undergone bypass grafting prior to aortic valve replacement. The proximal ends of the grafts were either anastomosed high on the aortic root or else individually cannulated to provide continuous distal perfusion during subsequent aortic valve replacement, with continuous coronary ostial perfusion. There were three operative deaths (6.1%) and one myocardial infarction (2.0%). The risk of combined aortic valve replacement and coronary bypass need be no greater than the risk of aortic valve replacement alone. Our experience suggests that myocardial perfusion distal to significant coronary artery stenoses reduces the risk of myocardial infarction in patients with coronary artery disease requiring aortic valve replacement.