Sixty-nine patients (48 primigravidae and 21 multigravidae) with 12 hours of spontaneous premature rupture of membranes (PROM) after 36 weeks gestation were randomly allocated to receive either prostaglandin E2 (PGE2) oral tablets or intravenous oxytocin to stimulate labor. The two treatments were compared regarding stimulation - delivery interval (SDI), analgesic requirements, maternal and fetal side effects, and patient acceptability. The mean SDI was shorter in the oxytocin group, but without statistical significance. Analgesic requirements and fetal side effects were similar in the two groups, but there was a higher incidence of nausea and vomiting in those patients receiving the maximum dose (1 mg hourly) of PGE2. On subjective assessment, clinicians considered oxytocin to be more effective (p less than 0.05), while midwives felt both regimes to be equally helpful. PGE2 oral tablets were significantly (p less than 0.05) more acceptable to the patients, who preferred the convenience of oral dosing, the absence of an i.v. line and the increased mobility. It is concluded that PGE2 tablets are a safe and effective method of stimulating labor following PROM, and highly acceptable to parturients. In those women in whom labor has not been established within 8 h of initiating PGE2 therapy, or in whom gastric side effects are troublesome, intravenous oxytocin should be substituted.