Obstetric hemorrhage is still a potential cause of maternal mortality and morbidity. Angiographic embolization techniques have been described in cases of postcesarean bleeding, vaginal wall hematomas, cervical ectopic pregnancies, and postpartum bleeding to control persistent bleeding from pelvic vessels. We describe two cases of pregnancy complicated with placenta percreta. Balloon occlusion and embolization of the hypogastric arteries were performed during the cesarean section and hysterectomy, resulting in a remarkable reduction in intraoperative blood loss. Balloon occlusion and embolization of the internal iliac arteries significantly reduce intraoperative blood losses. (Am J Obstet Gynecol 1997;176:723-6.)