Heterologous sarcomas of the uterus are rare neoplasms. A case of a pure leiomyosarcoma with a poorly differentiated liposarcomatous component is described. No carcinomatous elements were identified, thus excluding the possibility of a mixed mullerian tumor. This is the third report of such an entity in the medical literature. The disease in this patient was characterized by pulmonary metastases and recurrent disease in the abdomen developing within 5 months of optimal surgical debulking. It is speculated that totipotential primitive cells may have the ability to differentiate into an aggressive heterologous tumor.