Ten patients undergoing aortocoronary bupass surgery were studied during induction of anesthesia and during initial surgical stimulation. Each patient was anesthetized with fentanyl, 100 micrograms/kg, droperidol, 0.15 mg/kg, and pancuronium, 0.1 mg/kg, and ventilated with 100% oxygen. Preoperative medication consisted of propranolol, nitrate preparations, diazepam, 0.15 mg/kg orally, morphine, 0.15 mg/kg IM, and scopolamine, 0.4 mg IM. Intravenous, arterial, and Swan-Ganz catheters were inserted under local anesthesia after which control measurements of hemodynamic parameters and arterial blood gas tensions were taken. Observations were repeated after fentanyl, 50 micrograms/kg, after endotracheal intubation, after another dose of fentanyl, 50 micrograms/kg, after skin incision, and after sternotomy. The total dose of droperidol was given incrementally throughtout the fentanyl infusion. Normal saline was infused to maintain constant pulmonary capillary wedge pressure. Heart rate, left ventricular stroke work index, triple index, pulmonary capillary wedge pressure, and PaCO2 remained constant throughout the study. Systolic blood pressure decreased significantly after fentanyl, 50 micrograms/kg, and initial administration of droperidol, but thereafter remained unchanged. Stroke index increased significantly after fentanyl, 50 micrograms/kg, and remained elevated at all subsequent intervals. Cardiac index increased after fentanyl, 50 micrograms/kg and 100 micrograms/kg. Rate-pressure product was stable until the time of sternotomy after which it decreased significantly. In patients undergoing aortocoronary bypass surgery, 100% oxygen, fentanyl, 100 micrograms/kg, and droperidol, 0.15 mg/kg, produced stable hemodynamics during induction, intubation, and sternotomy. Maintenance of pulmonary capillary wedge pressure by volume infusion may have been contributed to this stability.