Giant aneurysm projected into the sellar region is a rare cause of hypopituitarism and is usually associated with atherosclerosis, fibromuscular dysplasia and pituitary radiation therapy. We report the case of a 78-year-old patient presenting a giant internal carotid artery aneurysm disclosed by clinical features of hypopituitarism and cranial nerves compression (optic and abducent). Computed tomographic scans, magnetic resonance images and cerebral angiography were performed and showed the aneurysm. Cerebral angiography confirmed concomitant atherosclerosis and fibromuscular dysplasia. After evaluation of risk/benefit, no surgical treatment was proposed. Replacement endocrine therapy with glucocorticoid and levothyroxine was initiated followed by a satisfactory clinical response.