In a prospective randomized study, patients with a valid obstetric indication for induction of labor received either 3 mg prostaglandin E2 vaginal pessaries immediately prior to oxytocin (prostaglandin group, n = 99), or oxytocin alone (oxytocin group, n = 103). At the conclusion of the second day of induction, a significant reduction was noted in the incidence of failed induction in the prostaglandin group (4%) as compared to the oxytocin group (13%) (p less than 0.05). Twenty percent of patients in the prostaglandin group experienced successful induction with prostaglandin pessaries only. When oxytocin was required in the prostaglandin group, the maximal concentration of oxytocin infused and the duration at this concentration were significantly less than in the oxytocin group. No perinatal complications were attributed to the use of prostaglandin. Three minor maternal complications that were attributed to vaginal prostaglandin E2 did not require treatment. Our conclusion is that patients who require an induction of labor, when artificial rupture of the membranes is not feasible, benefit from the use of prostaglandin pessaries before the administration of oxytocin.