Teratomas of the central nervous system are rare and are frequently found in children and young adults. Cystic teratomas found in infancy is a well-recognized but infrequent entity. Intracranial teratomas,like teratomas in general, tend to arise from midline structures such as the pineal gland, but has rarely been found in the third ventricle. We report a rare case of a 6-month-old infant with a mature cystic teratoma of the third ventricle with a review of literatures