In a random double-blind trial in 28 pregnant women at term, labour was induced with either prostaglandin F2alpha or oxytocin given by intravenous infusion. The results showed that prostaglandin F2alpha was as active as oxytocin and induction was successfully carried out in 24 patients; 3 patients had a caesarean section because of an obstructed labour and 1 patient on oxytocin did not have regular contractions after 10-hours' infusion although she delivered spontaneously 2 days later. No difference was found in the induction--delivery interval in the 8 patients in each group who had early amniotomy (first 90 minutes). No adverse effects were noted in either mother or the child. The authors recommend that to avoid side-effects the dosage of 20 mug prostaglandin F2alpha per minute should not be exceeded and that, although no cardiotocographic abnormalities were noted, this method of control should be used.