A case of craniopharingioma developed and situated in the cavity of the third ventricle with no connections with the base of the skull is reported. The patient was a thirty-year-old man, who within a few months had developed a diencephalic syndrome followed by psychic disorders and intracranial hypertension. Cerebral scan: large area of accumulation in the supra and retrosellar region. Bilateral carotid angiogram: no pathological staining but the venous angle and the internal cerebral vein were elevated and shifted posteriorly. Pneumoencephalogram: free and normal basal cisterns; the third ventrical is almost totally filled by a mass; small dilatation of the lateral ventricles. Operation: right trans ventricular approach to the third ventricle. The tumour was the size of an apricot encapsulated with a smooth surface, and adherent to the wall of the third ventricle only in the region of the infundibulum. There was little bleeding and no cystic component. Total removal was performed except for a few millimeters of capsule in the infundibular region. The postoperative course was complicated by an irreversible diencephalic insufficiency with death on the 27th postoperative day. Autopsy clearly showed that the inferior surface of the brain in the diencephalic region was not involved by the mass which hystologically was doubtless a craniopharingioma. Only two other cases of craniopharingioma of the third ventricle were so far reported in the literature by Cashion and Young in 1971.