A case of endometrial stromal sarcoma of the uterus with rhabdoid features, occurring in a 57 year old woman is reported. Electron microscopy and immunohistochemistry revealed that the rhabdoid cells contained intermediate filaments which were positive for vimentin, cytokeratin, alpha-smooth muscle actin, and muscle specific actin, but not for myoglobin and desmin. This indicated that the tumor in this case differed somewhat from the three rhabdoid tumors and an endometrial stromal sarcoma with rhabdoid differentiation previously reported and that, therefore, these tumors were heterogeneous.