The effect of labetalol on induced hypotension was studied in 13 patients undergoing major spine surgery. Hypotension was induced with initial dose of labetalol 0.4 mg/kg i.v. followed by 0.01 mg/kg/min i.v.infusion. BP, HR, and CVP were measured before, during, and after hypotension. Anesthesia was maintained with isoflurane (0.5-2 vol%) and N2O in 50% O2 supplemented by pancuronium. The time to systolic BP 75-85 mmHg or mean BP 55-65 mmHg was 18.5±2.8min and the time for systolic BP to recover 90% of prehypotensive value was 45.5±4.2 min. Heart rate was reduced signiTicantly after hypotension but remained stable at 80-90 beats/min thereafter. Central venous pressure showed no significant change irrespective of hypotension. The results suggest that combined use of fentanyl with labetalol or disuse of pancumnium may reduce the required dose of labetalol.