To investigate the suitability of the intratracheal (IT) route as an alternative route for the administration of vecuronium, we compared the pharmacodynamic parameters for neuromuscular block in three groups of rats given vecuronium via the IT, IM, and IV routes. We also examined the pharmacokinetics of vecuronium in the three groups. The doses for the IT, IV, and IM groups were set at 1.50, 0.300, and 2.25 mg/kg, respectively. The onset of action in the IT group (127 +/- 17 s) was significantly earlier than that in the IM group (267 +/- 62 s), and significantly later than that in the IV group (18 +/- 7 s) (P < 0.05 by analysis of variance and the Tukey-Kramer analysis). The duration of action in the IT group (794 +/- 162 s) was significantly longer than that in the IV group (93 +/- 30 s) but not significantly different from that in the IM group (743 +/- 131 s). The recovery index in the IT group (134 +/- 30 s) was significantly shorter than that in the IM group (222 +/- 47 s) and significantly longer than that in the IV group (32 +/- 12 s). Although IT administration of vecuronium is still slower than IV administration, it appears to be more advantageous as compared with IM administration, given the more rapid absorption and faster onset of action.