Ependymoma is a rare tumor entity. It affects children and adults and has four preferential locations: supra- and infra-tentorial, spinal, and conus-cauda-filum. For statistical reasons, therefore, it is difficult to identify prognostic factors in series from single institutions because of the limited number of cases. The problem is complicated by the existence of some variants and by the difficulty in recognizing the anaplastic variant, because the common criteria used for recognizing malignancy in gliomas are not completely reliable in ependymomas. Apart from age and location, many parameters have been considered for prognostic purposes, including extension of surgical removal and radiotherapy. Among histological factors, the number of mitoses, labelling indices of proliferation markers, and cell density turned out to be good parameters for prognostic purposes. An overview is given of the contributions in the literature, including our own, on this problem.