Primary intrinsic oligodendrogliomas of the brainstem are exceedingly unusual. The authors report the case of an intraaxial brainstem oligodendroglioma in an adult. In an extensive review of oligodendrogliomas, only six (0.4%) of 1593 cases recorded could be identified as intrinsic brainstem tumors. Five of these cases were found in children. This report documents a 25-year-old woman with a pontomedullary oligodendroglioma. An analysis of the world literature on this tumor type finds that posterior fossa oligodendrogliomas present at an earlier age and appear to be more aggressive biologically than their supratentorial counterparts. The overall prognosis for patients harboring an intrinsic brainstem oligodendroglioma remains unclear, with significant variability between patients.