A prospective, randomized, double-blind, placebo-controlled study was undertaken to evaluate the safety and efficacy of a 3-mg prostaglandin E2 (PGE2) vaginal suppository for the initiation of cervical ripening before the induction of labor. All patients were required to have an initial Bishop score of 4 or les. The 3-mg PGE2 vaginal suppository was found to be an effective method of both cervical ripening and labor induction. Its use resulted in a highly significant improvement in the mean Bishop score compared with the placebo group (2.67 versus 0.55 points, P less than .00005). Its use also resulted in a significant reduction in the number of failed inductions (5 versus 23%, P less than .0005). Moreover, 68% of the patients treated with PGE2 labored after initial suppository placement, and 42% of these patients never required oxytocin augmentation of labor. However, there were three instances of uterine hyperstimulation/hypertonus following placement of the 3-mg PGE2 suppository, suggesting that perhaps a lower dose of PGE2 would improve its safety as a ripening agent without affecting its efficacy.