Abstract: Objective: To study clinical efficacy of lower dose of mifepristone combined with misoprostol. Methods: 120 women with amenorrhea less than 37 days for 2 groups randomly. Sixty women in group of lower dosage （experimental group）: these women were dosed with mifepristone 100 mg for oral taken and oral cavity misoprostol 0.4 mg for sublingual taken. Sixty women in group of conventional dosage（control group）: these women were dosed with mifepristone 150 mg and misoprostol 0.6 mg for oral taken. Under the premise of reducing the mifepristone and misoprostol dosage, check the women′s complete abortion rate, bleeding time after taking medicine, abortion time and side effects to see if they were superior than conventional scheme. Results: Three women and 2 women were not pregnant confirmed by serum hCG test in group of lower dosage and group of conventional dosage, vaginal bleeding（i.e. the menses）appeared after they took the medicine.There was no obvious difference in complete abortion rate of group of lower dosage and group of conventional dosage（P > 0.05）. Mean abortion time of group of conventional dosage was superior than that of group of lower dosage（P <0.05）; there was no obvious difference in bleeding time of group of lower dosage and group of conventional dosage after dosing（P > 0.05）. Side effects in group of lower dosage and group of conventional dosage were significant difference（P < 0.05）.Conclusion: Effect of mifepristone with misoprostol in small dosage for amenorrhea ≤37 d women′s hastening menses and preventing pregnancy was feasible and side effects were less.

Key words: Mifepristone, Misoprostol, Drug therapy, combination, Menstruation, Abortifacient agents, induced