OBJECTIVES: To study if misoprostol 400 microg, administered vaginally, increased the successful resolution of early miscarriage compared with placebo. DESIGN: Randomised, double blind placebo controlled study. SETTING: Sahlgrenska University Hospital, Göteborg, Sweden. SAMPLE: One hundred and twenty-six women seeking medical attention for early miscarriage. METHOD: Women with a non-viable, first trimester miscarriage were randomised to vaginal administration of misoprostol 400 microg or placebo. MAIN OUTCOME MEASURES: Main outcome measure was the proportion of successful complete resolution of miscarriage. Secondary outcomes were incidence of infection, bleeding, gastrointestinal side effects, pain, use of analgesics and length of sick leave between groups. RESULTS: Sixty-four patients were randomised to misoprostol and 62 to placebo. Eighty-one percent in the misoprostol and 52% in the placebo group had a complete miscarriage within one week of the primary visit (RR 1.57; 95% CI 1.20-2.06). Patients in the misoprostol group reported more pain as assessed on a visual analogue scale (60.4 [31.0] vs 43.8 [37.1] mm; P