Early first-trimester abortions were induced by a single intravaginal pessary containing 3 mg of 15 methyl prostaglandin F2 alpha methyl ester in 17 patients. The procedure was successful in 16 patients (94%). Intrauterine events were observed by means of serial ultrasonic B scans. Pain, bleeding, and dislodgement of the gestational sac had commenced within 6 hours. Significant gastrointestinal side effects occurred in the majority of patients despite medication but they were usually of short duration. Vaginal bleeding, which was not heavy, continued for about 10 days and during most of this time the uterus contained products of conception. It is concluded that the method is effective during the first 7 weeks of gestation.