Propofol (2,6-diisopropyl phenol) is chemically unrelated to the other intravenous anesthetic agents. The compound is an oil at room temperature and is formulated as an 1% emulsion in soybean oil and egg phosphate. Rapid induction of anesthesia and recovery suggest that it will be valuable for ambulatory patients who are undergoing brief procedures and for sedation in intensive care units. The original formulation of propofol in cremophor may potentiate vecuronium neuromuscular blockade in both experimental and dinical setting. There were a little reports interaction between the emulsion formulation of propofol and vecuronium This study was designed to investigate the effect of propofol on the recovery period of vecuronium neuromuscular blockade in humans. Neuromuscular block was monitored by measuring the force of contraction of the adductor pollicis muscle after train of four stimulation of ulnar nerve, using ABM (Anesthesia and Brain activity Monitor, Datex CO, Finland). Fourty-two patients undergoing gynecological operations were included. All patients conformed to ASA physical states class 1 or 2. All patients were anesthetized by continuous lumbar epidural block with 1.5% lidocaine 4 mg/kg followed by general anethesia, with droperidol, 2.5% pentothal sodium, and vecuronium administered intravenously. Patients were classified 3 groups, as follows ; Group I (control group n=14): vecuronium 0.1 mg/kg i.v. only Group II (n=14): propofol, 1 mg/kg i.v. at the recovery time of Train of Four ratio 25% Group III (n=14): propofol, 2 mg/kg i.v. at the recovery time of Train of Four ratio 25% We monitered the recovery index (TOF 25-50%, 25-75%) and the time and degree of maximal depression in propofol groups. Results were as follows', 1) Recovery Index-50 (TOF 25-50%): The recovery time from TOF 25% to 50% were, 332+/-47.2, 445+/-54.3, 765+/-292.0 secs in groups I,II,III, respectively. (p<0.05) 2) Recovery Index-75 (TOF 25-75%): The recovery time from TOF 25% to 75% were, 742+/-156.0, 948+/-194.0, 1494+/-499.0 secs, in groups I,II,III, respetively. (p<0.05) 3) The time and degree of maximal twitch depression after injection of propofol: 20+/-4.0% of maximal twitch depression were observed for 25+/-15.2 sec after injection of propofol in 3 patients of Group II, and 17+/-4.8% of maximal twitch depression were observed for 190+/-130.0 sec after injection of propofol in 7 patients of Group III. With the above results, we concluded that propofol has a synergistic effect on the recovery period of vecuronium induced neuromuscular blockade.