Abstract: Ultrastructure of normal proliferative endometrium, cystic and adenomatous hyperplasia as well as well-differentiated endometrial carcinoma (5 cases for each group) were studied bystereologic morphometry. The results showed that with endometrial cell passing through its course of evolution to carcinoma, organelles of the cells probably first exhibited functional compensatory changes so as to fulfill the need of rapid cell proliferation and accelerated matabolism As the course went further, many organelles in which physiological reaction to estrogen was progressively lost presented degenegation in morphology. In our opinion, the stereologic morphometry could reflect morphologic cheracteristics of endometrium more objectively and prccisely.