Vecuronium bromide is a nondepolarizing neuromuscular blocking agent with minimal effect on the autonomic nervous system and little or no histamine release. Some investigators have found that as the dose of vecuronium increased from its ED the onset time is decreased. This study was designed to investigate the influences of a divided dose and single large dose on onset time of vecuronium in 40 ASA physical status l and 2 adult patients. The patients were divided into two groups: Gp. l; Priming dose(0.01 mg/kg) of vecuronium 4 minutes prior to intubating dose(0.14 mg/kg) Gp. 2; Single bolus intubating dose(0.15 mg/kg) of vecuronium followed immediately the induction agent. The results were as follows. l) After the priming dose administration, in the Gp. 2, 13 patients complained of side effcts. 2) The onset time (from the end of injection to l00% depression of the twitch tension) were 172.0±23.8 seconds in the Gp. I and 164.0±27.5 seconds in the Gp. 2. 3) Clinical duration of blockade (from the end of injection to first return of the second twitch of TOF) was 39,2±6.4 minutes in the Gp. l. In conclusion, we recommend the single large dose of vecuronium(0.15 mg/kg) for the endotracheal intubation in whom SCC is contraindicated.