It is known that when misoprostol is given at 200 microg every 3 h after mifepristone pretreatment, the vaginal route is more effective than the oral route. However, women prefer the oral route. This randomized study was to test our hypothesis that oral misoprostol 400 microg is as effective as vaginal misoprostol 200 microg when given every 3 h in termination of second trimester pregnancy after priming with mifepristone. A total of 142 patients was randomly assigned to group 1 (200 mg mifepristone + 400 microg oral misoprostol every 3 h up to five doses) or group 2 (200 mg mifepristone + 200 microg vaginal misoprostol every 3 h up to five doses). The incidence of side-effects and the preference study were assessed through a standardized questionnaire during and after the abortion. For the oral group, both the incidence of diarrhoea (40.0 versus 23.2%, P = 0.03) and the amount of drug used (1734 compared with 812 microg, P < 0.0001) were significantly higher than that of the vaginal group but the incidence of fever appeared to be lower (not significant). There was no significant difference in complete abortion rate: 81.4% in the oral group and 75.4% in the vaginal group. The median induction-abortion interval was similar in the two groups (10.4 versus 10.0 h). The percentage of women who aborted in 24 h was also similar: 57/70 (81.4%) in the oral group and 58/69 (87.0%) in the vaginal group. Overall, 82.0% of women preferred the oral route. Oral misoprostol (400 microg) given every 3 h up to five doses, when combined with mifepristone, was as effective as the vaginal (200 microg) route in second trimester termination of pregnancy. This regimen could also be offered to those women who found repeated vaginal administration unacceptable.