Intracranial teratomas and teratoid tumors are rare, constituting about 0.5% of the total Except germinomas or atypical teratomas, malignant teratomas almost always dysplay some tissue elements which are embriologically immature. Predilection sites of intracranial teratomas are the pineal body, the pituitary region and the posterior fossa in order of frequency. We have reported a case of malignant teratoma experienced in a 16 year-old boy who disclosed occipital headache and dizziness for 3 weeks. The tumor was located at the roof of the third ventricle and resulted in hydrocephalus. Histopathologically, were there variegated structures such as irregular glandular structures which were lined by a single or multiple layers of polygonal or spindle cells. A gland lined by cells having acidophilic secretory material in their cytoplasms and myxoid spindle cells suggesting immature mesenchymal tissue were also encountered.