BACKGROUND: Laryngoscopy and tracheal intubation may cause a hemodynamic change such as hypertension and tachycardia. Various drugs including esmolol and fentanyl have been used to reduce the hemodynamic change accompaning laryngoscopy and tracheal intubation. The purpose of this study was to investigate an optimal dosage of alfentanil for attenuating hemodynamic change. METHODS: The authors studied 108 ASA class 1 2 patients, scheduled for elective surgery, divided randomly into 5 groups. Anesthesia was intravenously induced with thiopental sodium (5 mg/kg) followed by vecuronium (0.13 mg/kg), and 2 minutes later (at 1 minute before intubation), group 1 (CONT group) received no alfentanil, and groups 2, 3, 4, and 5 (A10, A20, A30, A40 groups, respectively) received 10, 20, 30, or 40mug/kg alfentanil, respectively. The hemodynamic changes (systolic blood pressure, mean arterial blood pressure, diastolic blood pressure and heart rate) were measured at preinduction (base), postinduction (immediately before intubation), intubation, and postintubation (1 minute, 2 minute, 3 minute, 4 minute, 5 minute, 6 minute, and 7 minute after intubation). RESULTS: The hemodynamic changes in the A10, A20, A30, A40 groups were significantly lower than in the CONT group, but the incidence of hypertension was higher in the CONT, A10 groups at 1 and 2 minutes after intubation. The incidence of bradycardia and hypotension was higher in the A30, and A40 groups. CONCLUSIONS: When anesthesia was done with induction of thiopental sodium and vecuronium, the authors suggest that the recommended dosage of alfentanil for attenuating hemodynamic change accompaning a laryngoscopy and tracheal intubation is about 20mug/kg.