ObjectiveTo compare the efficacy of vaginal with oral misoprostol in termination of second-trimester pregnancy after pretreatment with mifepristone.MethodsWomen requesting termination of secondtrimester pregnancy were randomized into two groups. Thirty-six to 48 hours after oral administration of 200 mg of mifepristone, women were given either oral or vaginal misoprostol 200 μg every 3 hours for a maximum of five doses in the first 24 hours. Women receiving oral misoprostol also were given a vaginal placebo (vitamin B6), whereas those receiving vaginal misoprostol were given an oral placebo. If they failed to abort, a second course was given by the same route.ResultsThe median induction-abortion interval in the vaginal group (9 hours) was significantly shorter than that in the oral group (13 hours). The percentage of women aborting within 24 hours in the vaginal group (90%) was significantly higher than that in the oral group (69%). The median amount of misoprostol used in the vaginal group (600 μg) also was significantly less than that in the oral group (1000 μg). There was no significant difference in the incidence of side effects between the two groups except for fatigue and breast tenderness, which were more common in the oral group. Seventy-six percent of the women preferred the oral route, and 24.5% of the women preferred the vaginal route.ConclusionVaginal misoprostol is more effective than oral misoprostol in termination of second-trimester pregnancy after pretreatment with mifepristone, but more women preferred the oral route.