✓ Clinical characteristics of six cases of germinoma involving a unilateral basal ganglion and thalamus are summarized. The incidence was estimated as 10% of all intracranial germinomas. The average age at the onset was 10.5 years. The sex incidence showed a male dominance. The clinical course was slowly progressive, and the average duration between onset and diagnosis was 2 years 5 months. Common symptoms and signs were hemiparesis in all cases, fever of unknown origin and eye symptoms in most, mental deterioration and psychiatric signs in three, and convulsions, pubertas praecox, and diabetes insipidus in two. Signs of increased intracranial pressure were found in only two cases in the later state of the disease. Early diagnosis is difficult because of nonspecific symptomatology and slow progression. Carotid angiography and pneumoencephalography showed abnormal findings compatible with basal ganglia and thalamic tumors, but not specific to germinoma. Ipsilateral cortical atrophy and ventricular dilatation might be significant findings. Radioisotope scanning was useful. Computerized tomography scans were the best method of detecting the location and nature of this tumor, and repeat scans showed response to radiation therapy.