BACKGROUND: The studies related to induced hypotention using propofol were rare. So we studied the effectiveness of propofol as induced hypotensive agent in brain aneurysmal surgery. METHODS: The hemodynamic changes during induced hypotension with propofol (propofol-group) and isoflurane(isoflurane group) were observed in patients undergoing aneurysmal surgery. Twenty patients were allocated randomly to receive propofol induction and maintenance, or thiopental sodium induction and isoflurane maintenance for anesthesia. Both groups also received fentanyl, vecuronium, nitrous oxide and oxygen. These hypotensive effects were evaluated before, during and after induced hypotension. Hemodynamic changes were evaluated by measuring systemic arterial blood pressure, heart rate, central venous pressure, pulmonary capillary wedge pressure, cardiac output, systemic vascular resistance and pulmonary vascular resistance. We also compared the ventilatory effect of hypotensive anesthesia by blood gas analysis. RESULTS: There were no significant changes of heart rate, cardiac output, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, central venous pressure and pulmonary vascular resistance before, during and after induced hypotension in both group. Mean arterial pressure and systemic vascular resistance were significantly decresed during induced hypotension (p<0.05). There were no significant changes of PO2, PCO2, HCO3 , base excess before, during and after induced hypotension in both group. CONCLUSION: Propofol is also an effective hypotensive agent comparable to isoflurane.