The initial and follow-up endometrial curettings from 17 patients with atypical hyperplasia (AH) and 4 patients with complex hyperplasia (CH) were reviewed. All cases were younger than 40 years and the duration of follow-up ranged from 7 months to 38 years (mean, 11.3 years). According to the ISGP classification, the histological diagnostic criteria based solely on the presence of cytologic atypia. Twenty of them received progestin treatment and the lesion regressed at some time, but relapsed eventually. Twelve of them were performed hysterectomy after repeat progestin administrations and only 2 (11.8%) of 17 patients with AH progressed to invasive carcinoma 6 to 8 years later; however, all 4 patients with CH and 2 patients with milder forms of AH became pregnant and had normal term deliveries during the follow-up period. The histological diagnosis, prognoses and the effects on fertility in patients with AH and CH are discussed.