Abortion was successfully induced by intravaginal insertion of a silicone rubber device impregnated with an 0.5% concentration of 15(S)-15-methyl-prostaglandin F2alpha methyl ester in 20 of 25 patients by prostaglandin alone and in an additional three patients by prostaglandin with a concomitant oxytocin infusion. The mean abortion time for the 23 successful abortions was 15.46 hours. Uterine activity was monitored in six patients and uterine response to the vaginal insertion of the prostaglandin-impregnated device was characterized by a gradual rise in amplitude of contractions and intrauterine baseline tonus accompanied by a rapid increase in the frequency of contractions. Induction of abortion by intravaginal administration of a silicone rubber device impregnated with prostaglandin eliminates the hazards associated with intra-amniotic instillation and offers the advantage of a single administration with the option of reversibility if a patient should be hypersensitive to the drug.