OBJECTIVETo evaluate oral misoprostol use before office endometrial biopsy.METHODSForty-two nonpregnant women aged 35–77 years were randomized to a prospective, double-blind study to receive either 400 μg oral misoprostol or placebo 3 hours before office endometrial biopsy. Misoprostol effects were assessed by 1) cervical resistance, 2) ease of performing the endometrial biopsy, 3) success rate of obtaining an endometrial biopsy, 4) pain intensity associated with the endometrial biopsy, and 5) adverse clinical side effects.RESULTSPatients in the misoprostol group experienced significantly (P< .01) more pain associated with the endometrial biopsy. The observed power to detect this difference in misoprostol-placebo comparison using the Wilcoxon rank sum test at 0.05 level of significance is 89%. In addition, significantly (P< .05) more patients had the adverse side effect of uterine cramping at 1.5 hours after medication ingestion in the misoprostol group. The observed power to detect this difference is 98%. There were no differences between the misoprostol and placebo groups in cervical resistance, ease of performing the biopsy, success rate for obtaining an endometrial biopsy, or adverse side effects at 3 hours post medication ingestion.CONCLUSIONOral misoprostol 400 μg caused more uterine cramping and pain in nonpregnant women undergoing office endometrial biopsy when given 3 hours before biopsy attempt. No other cervical effects were noted.