In order to obtaine the constant, stable muscle relaxation, vecuronium was infused con-tinuously at fixed rate(0.06 mg/kg/hour) in 30 ASA class l & ll adult female Patients und-ergoing explorative laparatomy. All patients were premedlcated with Robinul 0.2 mg and hydroxyzine 1.5mg/kg IM 1 hour Prior to anesthesia. Starting infusion of vecuronium, anesthesia was induced with thiopental 5-6 mg/kg and vecuronium 0.08 mg/kg. Endotrach-eal intubatioo was Pperformed at 77~100% depresaion of twitch height monitored by train-of-four stimulation(2Hz) of the ulnar Nerve. Anesthesia was maintained with O2-N2O-enflurane. The patients were divided into three group: 1) Group l(n=10) : spontaneous recovery of neuromuscular block. 2) Group ll(n= 10) : reversed with neostigmine(0.02 mg/kg) at 25% twitch recovery after infusion stop. 3) Group lll(n= 10) : Reversed with same dose of neostigmine immediately after infus-ion Stop. The results were as follows ; 1) The onset times of 50% and 75-l00% twitch depression were average 122±23.72 sec. and 162±32.08 sec. respectively. 2) The neuromuscular response during infusion was well maintained less than 17% of control twitch height in all cases, and objeotive muscle relaxation was satisfactory. 3) The times of twice recovery from 25% to 75%(recovery index) were 27.9±13.02 min. in Group l, 8.6±4.44min. in Group ll, and 10.0±3.81min. in Group lll. Recovery index was shortened significantly in Group ll & ll adult female Patients und-ergoing explorative laparatomy. All patients were premedlcated with Robinul 0.2 mg and hydroxyzine 1.5mg/kg IM 1 hour Prior to anesthesia. Starting infusion of vecuronium, anesthesia was induced with thiopental 5-6 mg/kg and vecuronium 0.08 mg/kg. Endotrach-eal intubatioo was Pperformed at 77~100% depresaion of twitch height monitored by train-of-four stimulation(2Hz) of the ulnar Nerve. Anesthesia was maintained with O2-N2O-enflurane. The patients were divided into three group: 1) Group l(n=10) : spontaneous recovery of neuromuscular block. 2) Group ll(n= 10) : reversed with neostigmine(0.02 mg/kg) at 25% twitch recovery after infusion stop. 3) Group lll(n= 10) : Reversed with same dose of neostigmine immediately after infus-ion Stop. The results were as follows ; 1) The onset times of 50% and 75-l00% twitch depression were average 122+/-23.72 sec. and 162+/-32.08 sec. respectively. 2) The neuromuscular response during infusion was well maintained less than 17% of control twitch height in all cases, and objeotive muscle relaxation was satisfactory. 3) The times of twice recovery from 25% to 75%(recovery index) were 27.9+/-13.02 min. in Group l, 8.6+/-4.44min. in Group ll, and 10.0+/-3.81min. in Group lll. Recovery index was shortened significantly in Group ll & lll compaired to Group I (p<0.05), there was noStatistical Significantly between Group ll & lll. 4) There was no statistical significance between total dose of vecuronium used and reco-very inde% (P>7.05) . 5) Tidal volume and end-tidal CO2 tension before extuhation were within normal range in three group. 6) Abilities of open-eyes, tongue Protrusion, and head-lift for 5 seconds at recovery room were confirmed In all cartes. In conolusion, this technique is not definite in routine use. It would, however, be possible to adapt this infusion ramie to apply in male Patient, in patient with liver or kidney disease, or in long-term respiratorr care at intesive care unit.