Prolonged neuromuscular blockade following succinylcholine may be seen when anticho- linesterase had been administered prior to reverse nondepolarizing muscle relaxant-induced paralysis, possibly anticholinesterase has been reported to inhibit serum cholinesterase activity. Our study was undertaken in order to understand the effect of a nondepolarizing muscle relaxant (vecuronium) following neostigmine pretreatment. In this study, we assessed the effect of vecuronium induced neuromuscular blockade using a train of four, 2 Hz stimulations on ulnar nerve. Patients admitted to our hospital for elective operations were divided into two groups, each group consisting of 16 patients. In group I, vecuronium 0.1 mg/kg was .administered according to the priming principle following normal saline, in group II, vecuronium 1.0mg/kg was administered according to the priming principle following neostigmine 0.05 mg/kg and glycopyrrolate 0.003 mg/kg pretreatment. Then the time for Tl to reach 5% or less(second), and the time for Tl to reach from 25% to 75%(recovery index) were measured in both groups. The time for Tl to reach 5% or less in group I(92.8±14.72 second) and group II(97.5±16.43 seconds) were not siginificant. However the recovery indexof group I(10.2 5±1.93 minute) and group II(8.5±1.80 minute) showed significant shortening in group II(p<0. 05)