One hundred and twenty patients undergoing elective operations were randomly assigned to receive anesthesia with cither thiopental, 4 mg/kg-isoflurane, 0.2–3%-nitrous oxide, 60–70% (control) or propofol, 2 mg/kg-propofol infusion, 1–20 mg/min-nitrous oxide, 60–70% (propofol). Although anesthetic conditions were similar during the operation, differences were noted in the recovery characteristics. For non-major (superficial) surgical procedures, the times to awakening, responsiveness, orientation, and ambulation were significantly shorter in the propofol group (4 ± 3, 5 ± 4, 6 ± 4, and 104 + 36 min) than in the control group (8 ±7,9 ±7, 11 ±9, and 142 ± 61 min, respectively). In addition, less nausea and vomiting (20 vs. 45%) and significantly less psychomotor impairment was noted in the non-major propofol (vs. control) group. Following major abdominal operations, recovery characteristics did not differ between propofol and control groups. Delayed emergence (>20 min), significant psychometric impairment, and a high overall incidence of postoperative side effects (55–60%) were noted in both drug treatment groups. The authors conclude that propofol-nitrous oxide compares favorably to thiopental-isoflurane-nitrous oxide for maintenance of anesthesia during short outpatient procedures. However, for major abdominal operations, propofol anesthesia docs not appear to offer any clinically significant advantages over a standard inhalational anesthetic technique.