A 25-year-old man presented with headache and consciousness disturbance. MRI revealed well enhanced mass lesions using gadolinium at bilateral thalamus and right para lateral ventricle with mild perifocal edema. Obstructive hydrocephalus was observed. On neuroendoscoplc observation, the tumor was not appeared on the surface of the ventricle, therefore biopsy of the lesion was not sufficient to make a definitive pathological diagnosis. Third ventriculostomy was successful and the patient's consciousness improved. One week later, a stereotactic biopsy for right para lateral ventricle lesion made possible the histological diagnosis of typical germinoma. Post operative course was uneventful. Chemotherapy (CDDP and etoposide) following 30 Gy whole ventricle irradiation resulted in the complete response of the lesion. Four years later, he has no neurological deficit except for mild disturbance in his eye movement. Our experience suggests that a synchronous lesion at thalamus and para lateral ventricle seems to be due to subependymal infiltration other than CSF dissemination.