By women in climacterium and postmenopause the authors found 30 adenomatous atypical hyperplasias out of a total of 909 active hyperplasias. They also detected 68 endometrial carcinomas and 65 other changes. Out of 30 patients with adenomatous atypical hyperplasia, 23 had been subjected to curettage earlier but at that time had revealed only milder forms of hyperplasia. Surgery was performed in 21 patients: in 15 patients the diagnosis based on the operative preparation agreed with that based on curettage findings, in 2 patients endometrial carcinoma and in 2 patients glandular hyperplasia were detected, while in 2 patients there was no functional endometrium. Out of 9 patients who for various reasons were not surgically treated and represented an unintentional prospective study, 5 subsequently developed endometrial carcinoma, 3 mild forms of hyperplasia, and 1 atrophia cystica. In the authors' opinion, the histogenesis of endometrial carcinoma in late postmenopause is still an open question.