A randomized blinded investigation was undertaken to determine the efficacy and safety of sequentially applied intravaginal prostaglandin E2(PGE2) gel for accelerating cervical ripening in an outpatient setting in low-risk prolonged pregnancies. Fifty women with uncomplicated pregnancies at or beyond 41 weeks' gestation and Bishop scores below 9 received twice-weekly outpatient administration of gel containing 2.0 mg of PGE2or placebo. Thirty nulliparas and 20 multiparas were enrolled. The PGE2gel failed to improve cervical ripening over placebo, as judged by Bishop scores. There was no difference between the groups in gestational age on admission to the labor and delivery suite, number of gel applications, requirement for oxytocin, incidence of cesarean delivery, or neonatal outcome. Only two patients (4%) experienced regular uterine contractions after gel insertion; these subsided spontaneously in both. None of the subjects experienced labor, tetanic contractions, evidence of fetal distress, or any other side effects related to gel insertion. We conclude that PGE2gel in this dosage may be used safely in an outpatient setting, but more frequent application or earlier initiation may be required to produce a clinical effect