Objective: The purpose of this study was to determine whether the concurrent administration of oxytocin with sustained-release dinoprostone results in shorter induction times when compared with oxytocin after the removal of the dinoprostone insert. Study Design: Women with singleton pregnancies at ≥36 weeks, vertex presentations, reactive nonstress tests, no prior uterine scar, intact membranes, and Bishop scores of ≤6 were randomly assigned to receive oxytocin either immediately after placement of a sustained-release dinoprostone insert (immediate) or 30 minutes after its removal (delayed). The primary outcome was the time interval from induction to delivery. Results: Seventy-one patients were enrolled (immediate, 34 patients; delayed, 37 patients). There were no differences between treatment groups in nonreassuring fetal heart tracings, excess uterine activity, and epidural use. The mean time from dinoprostone placement until delivery was 544 minutes, shorter in the immediate group (972 vs 1516 minutes; P =.001). The proportion of deliveries within 24 hours was higher (90% vs 53%; P =.002) in the immediate group. Cesarean delivery rates were similar between the immediate and delayed groups (16% vs 13%; P =.73). No adverse maternal or neonatal outcomes were observed with concurrent therapy. Conclusion: Oxytocin that is administered concurrently with sustained-release dinoprostone significantly shortens induction-to-delivery times and results in a higher proportion of vaginal deliveries of ≤24 hours with no apparent adverse effects. (Am J Obstet Gynecol 2002;186:61-5.)