BACKGROUND: Some volatile anesthetics prolong the spontaneous recovery from neuromuscular blockade, and decrease the effect of neostigmine administrated for neuromuscular recovery. In addition, these effects differ among each volatile anesthetic. The aim of this study was to examine the effect of sevoflurane on the antagonism effect of neostigmine during the recovery period after administering rocuronium. METHODS: Sixty-five adult patients were randomly allocated into 3 groups, using propofol and alfentanil, sevoflurane, and enflurane for the maintenance of anesthesia. Neuromuscular monitoring was performed using accelomyography. Tracheal intubation was performed at the maximum blockade after administering 0.6 mg/kg rocuronium. The infusion of rocuronium was initiated when a twitch was noticed and the infusion rate of rocuronium was determined to maintain a 15 +/- 5% twitch height. The acid-base balance was measured at a constant twitch height, and 20microgram/kg neostigmine injection. After neostigmine, the initial twitch height, the maximum twitch height, the onset and duration of neostigmine were measured, and the antagonism effect was calculated as a percentage of the pre-existing twitch depression immediately before administering the neostigmine. RESULTS: The maximum twitch heights and antagonism effects of the Sevoflurane and Propofol groups were larger than that of the Enflurane group and the durations of the neostigmine effect were longer. The rocuronium infusion rate was significantly higher in the Propofol group than in the other groups. CONCLUSIONS: The effects of sevoflurane on the antagonism effect and duration of neostigmine were less than enflurane, and there was no difference between sevoflurane and propofol.