We compared anesthetic doses of three popular opiates, morphine (n = 10), fentanyl (n = 9), and sufentanil (n = 9) in patients undergoing cardiac surgery. Opiate administration after induction was based upon EEG and cardiovascular signs of the depth of anesthesia. Total doses were morphine, 4.4 +/- 0.71 mg/kg, fentanyl, 95.4 +/- 9.9 micrograms/kg, and sufentanil, 18.9 +/- 2.2 micrograms/kg. Comparisons among opiates included times for induction of anesthesia, return of consciousness, return of spontaneous ventilation, return of adequate cardiovascular status, and extubation. The following times (mean and SEM) were significantly (P less than 0.05) shorter for sufentanil than for fentanyl or morphine: induction (15 +/- 2.3 min, 5.9 +/- 0.7 min, and 3.0 +/- 0.2 min for morphine, fentanyl, and sufentanil, respectively); return of consciousness (morphine 109.7 +/- 34.4 min, fentanyl 62.3 +/- 17.9 min, sufentanil 17 +/- 8.7 min); return of acceptable and stable cardiovascular status (morphine 587.3 +/- 139.3 min, fentanyl 537.9 +/- 144.8 min, sufentanil 173.7 +/- 56.8 min); and extubation (morphine 1121.3 +/- 61.8 min, fentanyl 1005.7 +/- 77.7 min, sufentanil 533.3 +/- 67.8 min). We conclude that sufentanil administered in the dosage range of 19 micrograms/kg allows more rapid induction, earlier emergence from anesthesia, and faster extubation of patients than either morphine or fentanyl.