The natural history and the factors that lead to the acquisition of atypia in endometrial hyperplasias in young aged women, especially under the age of 20, have not been fully elucidated. In such cases, although there exists a considerable risk of progression to carcinoma, a conservative antiestrogenic treatment is primarily indicated, in attempt to preserve the reproductive ability of the young woman. We report of a 18-year-old girl with atypical hyperplasia of the endometrium, a diagnosis confirmed by reviewing of the histologic material by specialized gynecopathologists. The patient has been treated with gonadotropin releasing hormone agonist (leuprolide acetate) and tibolone for 1 year, which led to endometrial atrophy and amenorrhea, without hypoestrogenic side effects. Six months after cessation of the therapy the endometrial hyperplasia relapsed (this time without atypia), but in about 2 years of follow-up and after short courses of treatment with clomiphene citrate and progestins the biopsy of the endometrium revealed a functional endometrium and the patient presents with an almost regular menstrual cycle.