Two groups of healthy women at term, who were not in labor 3 hours after premature rupture of the membranes, were studied. In one group labor induction with oral prostaglandin E2(PGE2) was begun 3 hours after rupture, and in the other group intravenous oxytocin induction was begun 12 hours after rupture. PGE2was successful in initiating active labor in 88% of women treated. Of the women who were observed for 12 hours, one-half began labor spontaneously during that time. Women in whom labor was induced with PGE2given 3 hours after rupture of the membranes had a shorter interval of rupture to delivery, a lower cesarean section rate, and shorter postpartum hospitalization. Although significant bradycardia did not occur in fetuses of those women given PGE2, 10% of infants whose mothers were receiving oxytocin were delivered by cesarean section for this reason. It is concluded that oral PGE2is safe and effective for induction of labor in women with premature membrane rupture. The benefits, to both mother and fetus, of a shorter latent period are discussed. © 1977 The American College of Obstetricians and Gynecologists.