Abstract: Endometrial hyperplasia is defined as endometrial thickening with a proliferation of irregularly sized and shaped glands and an increased gland-to-stroma ratio. The specific cause of this disorder is unclear, the endometrium proliferation by estrogenic stimulation without progesterone resistance is believed to be the main etiological factor for developing the condition. Endometrial hyperplasia is currently mainly classified as endometrial hyperplasia with and without atypical hyperplasia according to the pathology. An atypical endometrial hyperplasia is considered as a pre-malignant conditions of the type Ⅰ endometrium. The diagnosis of endometrial hyperplasia should be taken into account of medical history, imaging and cytology, and its final diagnosis is based on histological results. The treatment of endometrial hyperplasia is mainly divided into medication and surgery. The specific treatment regimen should be based on the type of endometrial hyperplasia and the fertility requirements of the patient. This article reviews the endometrial hyperplasia definition, mechanism, diagnosis, classification, and treatment.

Key words: Endometrial hyperplasia, Diagnosis, Therapy