OBJECTIVE The purpose of this study was to compare the clinical efficacy and side effects of 3 doses of intravaginal misoprostol for second-trimester pregnancy termination. METHODS This was a prospective randomized, double-blind controlled clinical trial of 150 women who underwent pregnancy termination between 14 and 30 weeks of gestation. Three intravaginal misoprostol regimens were compared: 200 microg misoprostol at 6-hour intervals (group 1), 400 microg misoprostol at 6-hour intervals (group 2), and a loading dose of 600 microg misoprostol followed by 200 microg at 6-hour intervals (group 3). RESULTS There was a significant difference in the median time to achieve delivery among the 3 groups: group 1 (18.2 hours [IQ, 13.3-32.5 hours]) vs group 2 (15.1 hours [IQ, 10.9-23.7 hours]) vs group 3 (13.2 hours [IQ, 11.2-21.7 hours]; P =.035). Fifty-nine percent of the women in group 1, 76% of the women in group 2, and 80% of the women in group 3 delivered within 24 hours (P =.013). There were 7.8% of the women in group 1, 0% of the women in group 2, and 2% of the women in group 3 who were undelivered at 48 hours (P =.02). There was an increase in the incidence of fever in the first 12 hours (P =.038) and in the incidence of vomiting within 3 hours of the initial dose (P =.048) in group 3 compared with the other groups. CONCLUSIONS Intravaginal misoprostol 400 microg at 6-hour intervals appears to be the preferred regimen for second-trimester pregnancy termination, with a shorter commencement to delivery interval than the 200 microg regimen and fewer maternal side-effects than the 600 microg loading dose regimen.