Endometrial hyperplasia is a precursor to the most common gynecologic cancer diagnosed in women: endometrial cancer of endometrioid histology. It is most often diagnosed in postmenopausal women, but women at any age with unopposed estrogen from any source are at an increased risk for developing endometrial hyperplasia. Hyperplasia with cytologic atypia represents the greatest risk for progression to endometrial carcinoma and the presence of concomitant carcinoma in women with endometrial hyperplasia. Abnormal uterine bleeding is the most common presenting symptom of endometrial hyperplasia. Specific Pap smear findings and endometrial thickness per ultrasound could also suggest the diagnosis. Unopposed estrogen in women taking hormone replacement therapy increases the risk of endometrial hyperplasia. Tamoxifen has demonstrated its efficacy in treating women at risk for breast cancer, but it increases the risk of endometrial hyperplasia. The choice of treatment for endometrial hyperplasia is dependent on patient age, the presence of cytologic atypia, the desire for future childbearing, and surgical risk. Endometrial hyperplasia without atypia responds well to progestins. However, women with atypical hyperplasia should be treated with hysterectomy unless other factors preclude surgery.