Suppositories of 15-methyl PGF2.alpha. [prostaglandin F2.alpha.] methylester in triglyceride were administered vaginally to 75 women in whom 31 to 49 days had elapsed since their last menstrual period. Three or 4 suppositories of 0.5, 1.0 or 1.5 mg were given at intervals of 3 h. Pregnancy was later confirmed in 63 of the women. In the pregnant women vaginal bleeding usually started 3-6 h after the initiation of therapy and continued for 10-14 days. Patients were followed for 2-4 wk with serial measurements of serum progesterone and hCG[human chorionic gonadotropin]. There were no failures in the trial, but in 2 cases the treatment resulted in incomplete abortion. In 2 other patients curettage was performed due to prolonged bleeding, but histologic examination revealed no remaining signs of pregnancy. Gastrointestinal side effects were well within acceptable limits, and no serious complications occurred. Clinical signs of pelvic inflammatory disease were not found. The vaginal use of 15-methyl PGF2.alpha. methylester seems promising as a reliable outpatient nonsurgical self-administered procedure for termination of early pregnancy.