The clinico-pathological and immunocytochemical findings of 10 uterine fatty tumors (1 pure lipoma and 9 lipoleiomyomas) are referred. This kind of tumor is more frequent in older postmenopausal women, treated for a preoperative diagnosis of uterine leiomyoma. Macroscopically the tumor may show different consistence and colour as a consequence of the amount of lipomatous component. The microscopical detection of areas of perivascular immature mesenchymal cells with differentiation into adipocytes supports the hypothesis of "neometaplasia" of the lipomatous component derived from immature perivascular cells. On the contrary, the evidence of multivacuolation in smooth muscular cells and the presence of muscle markers in typical mature adipocytes in lipoleiomyomas, as revealed by immunocytochemistry, suggests the hypothesis of direct transformation of smooth muscle cells into adipocytes.