Pediatric posterior fossa tumors most commonly are pilocytic astrocytomas (PA), ependymomas, medulloblastomas, and atypical teratoid rhabdoid tumor (ATRT). MRI has some special radiological findings which can be used in the differential diagnosis. We report on the radiologic images and the clinical course of a 3 year-old-girl with oligodendroglial tumor arising from the cerebellum. There were no focal deficits in the neurological examination. MRI revealed a left cerebellar lesion extending into the left cerebellopontine region causing a pressure and shift in the fourth ventricle, pons and mesencephalon. She underwent a left occipital craniectomy and total tumor decompression. In the pathological examination, mainly oligodendroglial cells were seen in the tumor and they had round nucleus and perinuclear halos. No recurrence was detected at MRI and CT at 6 months postoperatively. Except for the following most common tumors as PA, ependymoma, medulloblastoma and AT/RT in the posterior fossa, the oligodendroglioma must be considered in the differential diagnosis.