OBJECTIVE To determine whether 15-methyl prostaglandin (PG) F2 alpha shortens the third stage of labor in second-trimester pregnancy loss. METHODS This was a randomized, double-blind, placebocontrolled study of women between 13 and 28 weeks' gestation admitted for spontaneous or induced pregnancy termination. Subjects were randomized on admission to receive either PG (250 micrograms) or placebo (normal saline), 1 mL intramuscularly every 20 minutes, for a maximum of three doses if the placenta had not delivered spontaneously within 10 minutes of the fetus. A dilute oxytocin infusion was given to women in both groups. The patients were managed expectantly with hourly vaginal examinations until intervention was required or up to 6 hours, when curettage was scheduled. RESULTS Thirty-eight women received PG and 29 received placebo. There was no difference between the groups with regard to method of pregnancy termination or gestational age. There was a statistically significant decrease in the time from first injection to placental delivery (40.0 versus 92.5 minutes; P = .02) between the PG and control groups, respectively. CONCLUSIONS The therapeutic use of PG in the third stage of labor in second-trimester pregnancy loss reduces the time to complete spontaneous placental delivery.