To assess the risks and benefits of vaginal delivery in patients with prior cesarean section, the English literature on this subject from 1950 to 1980 was reviewed. The following conclusions were reached: 1) Properly conducted vaginal delivery after cesarean section is relatively safe, with a 0.7% incidence of uterine rupture, 0.93 perinatal mortality, and no maternal deaths due to uterine rupture. 2) Of those patients allowed a trial of labor, 66.7% were successfully delivered vaginally. Successful vaginal delivery occurred in 74.2% of those patients with a nonrecurrent indication for their previous cesarean section and in 33.3% of those patients whose indication for previous cesarean section was cephalopelvic disproportion. Sixty-seven percent of those patients with a prior vaginal delivery versus 47.1% of those patients without a prior vaginal delivery subsequently delivered vaginally. 3) A classic uterine scar clearly increases the probability of uterine rupture. However, the precise magnitude of the increased risk cannot be accurately determined. 4) Certain basic safety requirements such as available operating room facilities and adequate personnel for careful observation are mandatory, but other management policies that remain controversial include use of regional anesthesia, oxytocin administration, timing of hospital admission, artificial rupture of membranes, mode of delivery, proper method to evaluate the uterine scar, and delivery of fetuses in breech presentation and twins. 5) A policy of selective vaginal deliveries among patients with prior cesarean sections will result in cost reductions due to decreased postpartum hospitalization.