Aneurysmal bone cyst is an uncommon lesion that occurs mainly in long bones and vertebrae, being the location in the sphenoid sinus extremely rare. Its origin is unknown, but it can be considered as a vascular phenomenon secondary to a primary lesion. Other primary diseases that may be associated to aneurysmal bone cyst are polyostotic fibrous dysplasia and giant-cell tumors. We report the case of a patient with an aneurysmal bone cyst in the sphenoid sinus causing vision dysfunction.