This study investigates the role of nicardipine hydrochloride in preoperative and intraoperative blood pressure control and intraoperative catecholamines (norepinephrine and epinephrine) release in 10 patients undergoing pheochromocytoma resection. Nicardipine was used orally in the preoperative period for either 1 or 8 days (60 to 120 mg/24 hr) and then was infused during anesthesia until tumor removal, continuously at a rate of 2.5 to 7.5 micrograms/kg/min, depending on systolic arterial pressure level. All patients were successfully operated on. No severe hypertensive crisis occurred during tumor manipulation, although several patients had a 3- to 85-fold (norepinephrine) and 3- to 40-fold (epinephrine) increase of catecholamines from baseline levels. Hemodynamics data suggest that nicardipine caused significant inhibition of vascular smooth muscle contraction (42% decrease in systemic vascular resistance); calcium-dependent catecholamines release was not inhibited by nicardipine infused as mentioned. Use of nicardipine may be recommended for perioperative and intraoperative control of pheochromocytomas and might substitute for routine alpha-adrenergic blockade.