BACKGROUND: The purpose of this study is to delineate hemodynamic changes resulting from endotracheal intubation under the effects of thiopental sodium and propofol using the thoracic electrical bioimpedance device. METHODS: Thirty healthy adult patients, scheduled for elective surgery under general anesthesia were randomly assigned to receive thiopental sodium 5 mg/kg (Group I, N=15), or propofol 2 mg/kg (Group II, N=15) for induction. Endotracheal intubation was performed following injection of succinylcholine 1 mg/kg. Anesthesia was maintained with enflurane 1.5-2.0% and 50% nitrous oxide in oxygen. Cardiovascular parameters were measured before induction of anesthesia, at the time of pre-intubation and immediate, 1, 2, 3 and 5 minutes after intubation. RESULTS: The mean arterial pressure was significantly decreased in the propofol group compared to that of the thiopental sodium group just after the post-intubation period (p<0.05). The heart rate were decreased in both groups but there were no significant changes in heart rate and cardiac output between group I and II. In group I, systemic vascular resistance was decreased but there was no significant changes between two groups. CONCLUSION: The data suggest that the usual doses of propofol could prevent the increase in mean arterial pressure following intubation due to systemic vascular maintenance. But the intubation of anesthesia using thiopental sodium could not prevent the increase in mean arterial pressure following intubation.