Objective: To examine the efficacy of vaginal misoprostol for mid-trimester pregnancy termination. Methods: This randomized trial compared misoprostol, 200 μg per vaginum q 12 h to a protocol of concentrated oxytocin plus low-dose vaginal prostaglandin E2 suppositories (10 mg q 6 h). Success was defined as an induction-to-delivery interval ≤24 h. Results: Interim analysis of the first 30 (15-misoprostol, 15-concentrated oxytocin) women demonstrated that the 2 groups were similar with regard to indication for delivery, gestational age, and demographic characteristics. Misoprostol was associated with a lower success rate (67 vs. 87%, P = .2), a longer induction-delivery interval (22 hvs. 18 h, P = .09), a higher rate of retained placenta requiring curettage (27 vs. 13%, P = .65), and a higher live birth rate (50 vs. 0%, P = .006). Conclusions: Compared to a regimen of concentrated oxytocin plus low-dose prostaglandin E2, misoprostol administered as vaginal tablets in a dose of 200 μg q 12 h is not satisfactory for mid-trimester pregnancy termination in an unselected population. © 1999 Wiley-Liss, Inc.