Abstract: Pathologic features of 8 patients with rare endometrial stromal tumors of the uterus were analysed. Microscopic findings were reviewed and according to the cri-teria of Norris and Taylor and Yoonessi et al, we proposed that 1) The tumors ineach instance consisted of homologous tissue resembling the malignant counterpartof endometrial stromal cells. None of them contained any elements of carcinoma ofheterologous differentiation. 2) In stromatosis, the neoplastic cells were arrangedin cohesive sheets and extensived into the myometrium consisted entirely of solitarysmall well-circumscribed mass, and in stromal sarcoma, diffusive sheets of thetumor cells were extensived into the myometrium combined with hemarrhage andnecrosis. 3) Mitotic activity and cellular atypical, stromal sarcoma have veryhigh mitotic rates that usually exceed 10 mitoses per HPF, while in the cases ofstromatosis generally manifest sparse mitotic activity, having fewer than 10 mitosesper HPF and frequently considerably less. The cel f stromal sarcoma also have anaplastic cytologic features that usually exceed those encountered in stromatosis.The histologic differential diagnosis was discussed.