Clinical, anatomical, and hemodynamic factors influencing the operative survival of 276 patients undergoing insertion of coronary artery bypass grafts were examined. A significant relationship was present between mortality and left ventricular performance. Left ventricular end diastolic pressure greater than 18 mm Hg, an arteriovenous oxygen difference greater than 6.0 vol%, an ejection fraction less than 25%, dyskinesia of left ventricular contraction, or mitral insufficiency were each associated with an increased surgical mortality. Significant stenosis of the main left coronary artery was associated with a 31% mortality, but this was reduced to 18% in those patients receiving grafts to both the circumflex and left anterior descending coronary arteries. In patients with severe disease of multiple arteries, the best results were obtained when it was possible to graft all involved major vessels.