Patients with severe ventricular dysfunction make up a special subset of patients who undergo coronary artery bypass procedures. For these patients, the risk associated with the bypass procedure is relatively high, but the opportunity-for-survival benefit is also greater. We studied 61 consecutive coronary artery bypass patients with preoperative ejection fractions < or = 25%, and further compared several subgroups: Group I (n = 30) ejection fractions ranged from 21% to 25%; Group II (n = 23) ejection fractions ranged from 16% to 20.9%; and Group III (n = 8) ejection fractions ranged from 10% to 15.9%. The overall mortality rate was 8% (5/61), with no deaths in Group III. The 41% (25/61) of patients who received left internal mammary artery conduits experienced a higher mortality rate, yet it did not differ significantly from that of patients who received only saphenous vein conduits. Intraaortic balloon pumps were placed in 48% (29/61) of the patients, with a progressively higher incidence in patients with poorer ventricular function (P < 0.05). Most intraaortic balloon pumps (59%) were placed intraoperatively. Two patients underwent placement of left ventricular assist devices, and 1 of these survived. Coronary artery bypass grafting in patients with poor ventricular function carries a substantial, but acceptable, mortality risk. Use of the left internal mammary artery did not improve perioperative mortality, and may have a negative impact in the early postoperative period. Intraaortic balloon pump use was most common in those patients with the worst ventricular function. Prophylactic intraaortic balloon pump use may be justified in candidates with ejection fractions < 20%.