Objective: To observe the clinical efficacy and safety of Yiweining (异位宁 , YWN) and gestrinone (GT) in treating post-operational patients of stage Ⅲ endometriosis (EM-Ⅲ). Methods: Fifty-two patients of EM-Ⅲ after operation were randomly assigned into three groups, the YWN group (20 patients)was treated through oral intake of YWN 200 mi, twice a day; the GT group ( 19 patients) treated with gestrinone 2.5 mg, twice every week, with the medication starting from the 7th post-operational day and lasting for 6 months. The control group (13 patients) was untreated. Six months was one therapeutic course, and follow-up study was carried out in the 6-30 months after the end of the medication. Results: The recurrence rate in the YWN group and the GT group were 5.0% and 5.3% respectively, showing insignificant difference between the two groups, but they were lower than that in the control group (30.7%, P＜0.05). Besides,the adverse reaction rate in the YWN group was lower than that in the GT group (10.0% vs 31.6%, P＜0.05). Conclusion: Application of YWN to prevent the post-operational recurrence of endometriosis is effective and safe, and its efficacy is.similar to that of GT.