ObjectiveTo compare the abortifacient efficacies of two intravaginally administered misoprostol doses and gemeprost in termination of second-trimester pregnancy.MethodsEighty-one women between 12 and 24 weeks' gestation requesting abortion were randomized to receive intravaginally either 100 μg of misoprostol at 6-hour intervals (n= 27), 200 μg of misoprostol at 12-hour intervals (n= 26), or 1.0 mg of gemeprost at 3-hour intervals (n= 28). The regimen was continued until abortion, or for 36 hours, with assessment of the rate of complete and incomplete abortions as well as side effects within 48 hours from the start of the treatment.ResultsThe final rates of terminations were 74% in the 100 μg misoprostol group, 92% in the 200-μg misoprostol group, and 89% in the gemeprost group. Abortion was complete in 37%, 61% and 32% in each group, respectively (P= .03, when the 200-μg misoprostol group was compared with the two other groups). The inductions- to-abortion interval was longer (P= .001) in he misoprostol groups (mean 23.1 hours for the 100-μg and 27.8 hours for the 200-μg dose) than in the gemeprost group (14.5 hours). There was less pain (P= .01), and vomiting (P= .01) in the misoprostol groups that in the gemeprost group. The mean blood loss in the misoprostol groups was lower than in the gemeprost group (P= .001).ConclusionIntravaginal application of 200 μg of misoprostol at 12-hour intervals in induction of second-trimester abortion is equally effective to a standard gemeprost regimen. Misoprostol causes fewer side effects and is cheaper and more practical to use.