The hemodynamic effects of a balanced anesthetic technique where a moderate dose of fentanyl (32 micrograms/kg) is supplemented with isoflurane were studied in 15 patients with good left ventricular function. Mean inspired isoflurane concentration was 0.63% during induction and 0.74% during maintenance. Induction of anesthesia was associated with a significant decrease (p less than 0.05) in systolic and diastolic pressure and left ventricular stroke work index (LVSWI). During maintenance systolic blood pressure and LVSWI remained significantly depressed. It is concluded that isoflurane-fentanyl anesthesia has myocardial depressant properties. There is a reduced incidence of break-through hypertension during noxious stimuli, when compared with high-dose fentanyl anesthesia. During maintenance, clinical signs that could reflect myocardial ischemia were not observed. Heart enzymes remained within normal range postoperatively in all patients and ECG morphology was unchanged.