SummaryA case of saccular aneurysm of the intrasellar segment of the right internal carotid artery resulting in diabetes insipidus was reported.The patient showed mental symptoms which accord with those found in the literature.These symptoms did not respond to hormone therapy nor was influenced significantly by chlorpromazine.The role of antidiuretic hormone, and hypophyseo ‐hypothalamic lesion in causation of mental symptoms were discusse