The introduction of prostaglandins into clinical practice has been one of the most important advances in obstetrics and gynaecology in recent years. During the last decade obstetricians have become familiar with these drugs for inducing labour and for terminating second-trimester pregnancy. Within the last year their use has been extended, in association with antiprogestin, to first-trimester termi nation. Although the effectiveness of prostaglandins in these pharma cological roles is clear, their full potential has still to be explored, and much remains to be learned about their physiology....