Twenty-four patients undergoing abdominal aortic surgery for aneurysm or occlusive vascular disease entered a randomized, double-blind protocol comparing high-dose narcotic anesthesia with fentanyl (125 μg/kg) or sufentanil (25 μg/kg). All patients received perioperative β-adrenergic blockade therapy. Hemodynamic and electrocardiographic (leads 11 and V 5) responses to induction, intubation, skin incision, aortic cross-clamping, and declamping were studied. Sufentanil produced a transient decrease in mean arterial pressure and a significant reduction of systemic vascular resistance during induction. However, no significant hemodynamic differences were observed between the two groups during intubation, or at any other time during surgery. To maintain mean arterial pressure within 20% of the awake control value, the fentanyl group required an average infusion of 1.0 ± 1.1 μg/kg/min of nitroglycerin compared with 1.7 ± 2.8 μg/kg/min for the sufentanil group. Low-dose isoflurane was required in 30% of patients in the fentanyl group, compared with 41 % of the sufentanil group, for control of blood pressure. The multiple-bolus technique of narcotic administration resulted in a wide but parallel range of plasma concentrations from induction to the end of surgery with both narcotics. Mean plasma fentanyl concentrations varied between 7.2 ± 1.4 ng/mL and 26.5 ± 7.9 ng/mL, and mean sufentanil plasma concentrations varied between 1.0 ± 0.1 ng/mL and 10.6 ± 7.2 ng/mL throughout surgery. Within this range of narcotic serum levels, the authors were unable to identify a specific threshold level for either narcotic above which hemodynamic responses were consistently attenuated. A low incidence (4.5%) of intraoperative myocardial ischemia was observed. It is concluded that sufentanil and fentanyl are not different at blunting hemodynamic responses during aortic surgery. When supplemented by low doses of nitroglycerin and isoflurane, both narcotics provide anesthesia characterized by good hemodynamic control and a low incidence of myocardial ischemia.