Objective To analyze the efficacy and safety of drugs on reverse of atypical endometrial hyperplasia in patients with polycystic ovary syndrome(PCOS).Methods Seventeen patients with PCOS complicated by atypical endometrial hyperplasia(9 patients who were treated with progestin but not reversed were considered as group A;8 patients who were untreated were considered as group B)were retrospectively analyzed. Both groups received oral glucose tolerance test(OGTT)and insulin release test,to check whether the patients had insulin resistance(IR)or hyperinsulinemia. The 17 patients were treated with oral contraceptives combined with metformin.Results After the 17 patients with PCOS complicated by IR and hyperinsulinemia received drug treatment for 3-6 cycles,atypical endometrial hyperplasia was successfully reversed.Conclusion Oral contraceptives combined with metformin is a clinically practical and effective method for treatment of PCOS complicated by atypical insulin-resistant endometrial hyperplasia. Objective To analyze the efficacy and safety of drugs on reverse of atypical endometrial hyperplasia in patients with polycystic ovary syndrome (PCOS). Methods Seventeen patients with PCOS complicated by atypical endometrial hyperplasia (9 patients who were treated with progestin but not selected were groups Both groups received oral glucose tolerance test (OGTT) and insulin release test, to check whether the patients had insulin resistance (IR) or hyperinsulinemia. The 17 patients were treated with oral contraceptives combined with metformin. Results after the 17 patients with PCOS complicated by IR and hyperinsulinemia received drug treatment for 3-6 cycles, atypical endometrial hyperplasia was formed treatment of PCOS complicated by atypical insulin-resistant endometrial h yperplasia.