BACKGROUND: Mivacurium is a non-depolarizing neuromuscular blocking agent which has short duration of action. The goal of this study was to describe a technique which could shorten the onset time of mivacurium for rapid endotracheal intubation by using priming principle. METHODS: Thirty-one patients were randomly allocated into four groups. Patients in group I(n=8) received a single dose of 0.12 mg/kg mivacurium. Those in group II(n=10), III(n=6), and IV(n=7) received 0.015 mg/kg pancuronium, 0.012 mg/kg vecuronium, and 0.008 mg/kg mivacurium 4 minutes before the intubating dose of 0.12 mg/kg mivacurium was given respectively. Accelerographic response to train-of-four(TOF) stimulation of ulnar nerve at 15 seconds interval was used for neuromuscular monitoring. The onset time, the duration and recovery indices were compared between groups. RESULTS: The onset time in group II (2.9 0.49 min) and III (2.33 0.4 min) were significantly faster than that in group I (5.19 0.47 min). In the group II, the duration (26.3 1.9 min) and recovery index (12.35 2.45 min) were significantly prolonged than those in group I (9.12 1.21 and 4.75 0.52 min), respectively. CONCLUSION: The onset time is more rapid when pancuronium or vecuronium is used as priming agent than when mivacurium as single bolus injection or priming agent.