Seventy-seven patients with endometrial hyperplasia, 48 with simple hyperplasia without atypia (SH), 17 with complex hyperplasia without atypia (CH), one with simple hyperplasia with atypia (SHA), and 11 with complex hyperplasia with atypia (CHA) were prospectively followed-up by total curettage every 12 months for 3 years. Progression to carcinoma occurred in only one of the 77 patients; she showed grade 1 adenocarcinoma. The overall regression rates were 79% for SH, 100% for SHA, 94% for CH, and 55% for CHA, respectively. In patients with CHA whose disease reverted to normal endometrium, regression was most likely to occur within the first year.