Germ cell tumors comprise 0.4-3.1% of all intracranial tumors, and teratoma constitutes 9-30% of them. Congenital intracranial tumors are very rare and only account for 0.5-1.5% of all childhood brain tumors. The most common type of these tumors present at birth is teratomas, which represent 0.5% of all intracranial tumors. Most teratomas are midline tumors located predominantly in the sellar and pineal regions. In this study, we report a neonatal intracranial immature teratoma at the lateral ventricle because of its rare location. A 5-day-old female neonate presented with a history of irritability and left eye protrusion since birth. A head computed tomographic (CT) scan and magnetic resonance imaging (MRI) disclosed a large tumor filling the left lateral ventricle and extending into the ipsilateral retro-orbital space. With left frontotemporoparietal craniotomy, a large grayish-white lobulated vascular mass was encountered, and total removal of tumor was performed. Histological examination revealed the diagnosis of immature teratoma. The prognosis of congenital intracranial immature teratoma is usually poor because the lesions are extensive when they are identified. Prenatal ultrasonography is necessary for the prenatal diagnosis. Fetal MRI should be made for the evaluation of intracranial tumor. If the tumor is detected before the 24th week of gestation, termination of the pregnancy should be considered. Copyright (C) 2007 S. Karger AG, Basel.