BACKGROUND: In this prospective, randomized, double-blind, placebo-controlled trial, we investigated the effect of a single dose of esmolol on the bispectral index (BIS) to endotracheal intubation during desflurane anesthesia. METHODS: After induction of anesthesia, 60 patients were mask-ventilated with desflurane (end-tidal 1 minimum alveolar concentration) for 5 min and then received either normal saline, esmolol 0.5 or 1 mg/kg, 1 min prior to intubation (control, esmolol-0.5 and esmolol-1 groups, n = 20/group). BIS, mean arterial pressure, and heart rate were measured prior to anesthesia induction and esmolol administration, immediately preceding intubation (time point 0), and every minute for 5 min after intubation (time point 1 to 5). At time point 0, 1 and 5, 5 ml of arterial blood was taken to measure plasma concentrations of norepinephrine and epinephrine. RESULTS: BIS increased significantly at 1 min after intubation when compared with pre-intubation values in all groups. Both mean arterial pressure and heart rate increased significantly 1 min after intubation when compared with preintubation values for all groups. Plasma epinephrine concentrations did not increase significantly after tracheal intubation in any of the groups. Norepinephrine increased at 1 min after intubation when compared with the preintubation values in the esmolol groups (P < 0.05). CONCLUSIONS: A single bolus of esmolol was unable to blunt the increase in BIS to endotracheal intubation during desflurane anesthesia.