The onset time of the non-depolarizing muscle relaxants can be shortened significantly when small dose of the same or different non-depolarizing muscle relaxant is administered prior to single sufficient dose. Likewise, the hypothesis that administration of neostigmine in divided dose accelerate the antagonism of neuromuscular blockade from "priming priciple" is not known, but under this Phenomenon the Present study was investigated the reversal effects following administration of neostigmine in divided dories compared wish single bolus dose. All patients were ASA physical status class l or ll undergoing minor surgery, free from neuromusfular, renal or hepatic diseases and not taking any drugs known to interfere with neuromuscular function. In all patients, anesthesia was induced with thiopental sodium (5 mg/kg) and endotracheal intubation preceding by vecuronium(0.08 mg/kg) and was mainteined with 50% N2O in oxygen and enflurane (1.0~2.0%) with continuous vecuronium infusion (0.06 mg/kg/hr). The EK7, heart rate, mean arterial prssure and nasopharrngeal temperature by Datascope 2100, and Train of four(T1 and T4) sequence 2 Hz every 20 second and end tidal CO2 using Datex ABM were monitored continuously. At the end of operation, continuous vecuronium infusion was discontinued but N2O and enflurane was received until all measurements were complete. When T1 had returned to 10% of control value, anticholinesterase mixture (anti-chE : neostigmfne 0.04 mg/kg) was admini-stered as following; Anti-chE was administered in a single bolus dose(control group, n=10), in an initial dose 20% of anti-chE(group l , n=10), in an initial dose 50% of anti-chE(group ll , n=7) and in an initial dose toff of anti-chIn(group lll, n=8) followed three minutes later by remaining dose for antagonism of vecuronium induced blockade respectively. The recovery of T1 twitch height was faster from 8 minutes in group l, and 5 minutes in group ll and lll after anti-chE administration, compared with control group, but group If was statistically insignificant. The recovery of T4 twitch height was faster from 9 minutes in group 1, 6 minutes in group ll and 8 minutes in group B after anti-chE administration compared with control gro-up but in group ll it was statistically ignificant. T4 recovery (TOF artio, fade) which depend upon T1 in three divided group was faster than control group. After anti-ch E administration, in all groups, heart rate was increased following decreased, and the change of mean arterial pressure within+/-6% after anti-chE administration was observed. In conclusion, the administration of anti-chE mixture(neostigmine 0.04mg/kg and and atr-opine 0.02mg/kg) in divided dose accelerated a significantly more rapid reversal of vecuron-ium infusion induced neuromusculas blockade as compared to a single administration, especially in an priming dose as 20% of anti-chE mixture.