A case of pilocytic astrocytoma of neurohypophysis is presented. The clinical, pathological and MRI features of a rare tumor of the neurohypophysis are described. A 5-year-old girl presented with a 3 month history of lethargy, imbalance and visual disturbances. A MRI revealed a large suprasellar mass. Histopathological examination demonstrated a pilocytic astrocytoma. Its astrocytic nature was confirmed by positive immunostaining for GFAP and the findings of an electron microscopy.