The neuromuacular blocking effects of the repeated bolus injection and continuous injection of vecuronium have been compared in 20 patients by means of evoked twitch tension. Group I received a loading dose (0.08 mg/kg) of vecuronium and followed by maintenance doae (0.02 mg/kg) when twitch tension had recovered to 25% of control. Group II received a loading doses (0. 08mg/kg) of vecuronium plus a continuous infusion delivering 0.06 mg/kg/hr. Anesthesia was maintained with nitrous oxide, oxygen and 1.5% enflurane. The neuromuscular blocking effect were reversed by the neostigmine 1.0 mg and robinul 0.2 mg when twitch tension had recovered 25% control in both groups near the end of operation. With repeated injection of vecuronium (group I), the duration of blockade of 25% recovery was 21.6±4.2 minutes and the recovery times from 25% to 75% was 6.8±1.9 minutes The continuous infusion of vecuronium (group II) produced consistent neuromuscular blockade at the average level of 90% twitch depression. The times from the end of infusion to 25% and fr,om 25% to 75% are averaged 16.0±2.5 and 4.2±0.7 minutes respectively. The reeovery index was more rapid in infusion group than maintenance group (P<0.05).