A 17-year-old female had headache for several weeks and she developed an episode of seizure one day prior to admission. She underwent both CT and MRI, which both revealed a large tumor with cystic and solid portions at the right frontoparietal convexity. During operation, a well-defined tumor was found to have a stalk connecting the tumor itself with the brain parenchyma, proving that it was growing exophytically and expanding into the subarachnoid space. Histopathological examination revealed an anaplastic ependymoma with high cellularity. We report here on this case of an unusual supratentorial ependymoma with exophytic growth, and this can be mistaken as another exophytic growing intra-axial tumor or even as an extra-axial tumor.