The antepartum diagnosis of pheochromocytoma concurrent with pregnancy has been reported in 42 cases. These cases were analyzed for the effect of preoperative alpha blockade and of the timing of surgical intervention. Alpha blockade, when performed promptly in all pregnant patients in whom the diagnosis of pheochromocytoma was made, reduced fetal mortality regardless of the gestational age. In addition, when the diagnosis of pheochromocytoma was made in the third trimester of pregnancy and alpha blockade was adequately maintained, a combined procedure of cesarean section and tumor resection was best. If the tumor could not be located during a combined procedure, delivery followed by delayed resection was not associated with any greater maternal mortality. The surgical approach required for patients diagnosed in the first or second trimester was less clear. Although alpha blockade is indicated in such early patients, it cannot yet be determined if a delay in the tumor excision will subject the mother and fetus to a greater risk than the accepted practice of early resection with delayed delivery.