This case describes a 13-year-old boy who had a suprasellar germinoma involving the bilateral basal ganglia. His presenting symptoms included left-sided weakness, diabetes insipidus, a decline in academic functioning as well as psychotic and obsessive-compulsive symptoms. His neuroradiological findings and clinical symptoms lend support to the potential role of the basal ganglia in psychotic and obsessive-compulsive symptomatology.