Vaginal application of tablets containing prostaglandin at term in pregnant women with a favorable cervical score is a very efficacious method of induction of labour. Due to the motility of the women they consider this method of induction as almost natural. We, therefore, aimed at discussing the optimal procedure in low-risk pregnancies at due date, by means of a prospective randomised trial. In 345 women with a favourable cervical score, labour was either induced by means of intravaginal application of tablets containing PGE2 according to a precise plan, or spontaneous onset of labour was awaited while CTG-controls were performed on an outpatient basis every second day until the 42nd week of pregnancy was completed. 80 per cent of the nulliparas and 96.3 per cent of the multiparas of the induction group delivered within 24 hours of the first tablet application. All pertinent delivery intervals were significantly shorter in this group compared to those women where spontaneous onset of labour was awaited. The incidence of prolonged labour was low in both groups and not significantly different. Only 4.2 per cent of the women in the group where spontaneous labour was awaited, reached the completed 42nd week of pregnancy. Only one woman had to be induced because of a suspicious CTG. The rate of operative deliveries was lower in the induction group (1.1% versus 3.8% Caesarean sections). With the exception of one foetal death due to a cord complication three days after the due date the foetal outcome was excellent in both groups. The acceptance of the procedure was tested by means of a questionnaire during the post partum period.(ABSTRACT TRUNCATED AT 250 WORDS)