Intraventricular neoplasms of the third ventricle represent a small minority of intracranial tumors. Furthermore, few cases of solitary, third ventricular glioblastoma multiforme were reported in the literature. The authors report a case of a fifty-nine year old man who presented with progressive gait disturbance, disorientation, diffuse headache, and vomiting. Computed tomography and magnetic resonance imaging (MRI) confirmed a solitary third ventricular ring-enhancing lesion and obstructive hydrocephalus. The final pathology of the lesion upon permanent section was glioblastoma multiforme (GBM). The clinical course, radiologic findings, the possible origin of this lesion, as well as possible treatment regimen are discussed.