BACKGROUND: The purpose of the present study was to determine the optimal dose of bolus remifentanil to attenuate hemodynamic changes to laryngoscopic double-lumen endobronchial intubation. METHODS: A total of 80 ASA I or II patients requiring double-lumen endobronchial intubation were randomly assigned to receive normal saline (NS) or one of the three different doses (0.5microgram/kg (group R0.5), 1.0microgram/kg (group R1.0) or 2.0microgram/kg (group R2.0)) of remifentanil. Study drugs for each group were administered over 30 seconds after induction of anesthesia with thiopental sodium and rocuronium. Laryngoscopic endobronchial intubation was carried out 90 seconds after the administration of study drug. Arterial blood pressure and heart rate were recorded at preanesthetic baseline, preintubation, postintubation, and every one minute during the initial 5 minute period after intubation. RESULTS: Mean arterial pressure at postintubation period increased significantly compared to baseline value in group NS, R0.5, and R1.0, but there were no significant changes in group R2.0. Heart rate showed significant increase in comparison to baseline value at every postintubation period in group NS, R0.5, R1.0, with no significant changes in group R2.0. CONCLUSIONS: We suggest that 2.0microgram/kg of remifentanil attenuate the hemodynamic changes to double-lumen endobronchial intubation without adverse effect.