Intrasphenoid rupture of a non-traumatic aneurysm of the cavernous carotid artery is rare. We describe a patient in whom this condition manifested with epistaxis and led to the formation of a pseudoaneurysm occupying the right sphenoid sinus. The lesion recurred after repeated attempts at conservative endovascular therapy. Eventually the patient was treated with endovascular occlusion of the right internal carotid artery. Our report emphasizes the relapsing behaviour of a non-traumatic aneurysm of the cavernous portion of the internal carotid artery ruptured into the sphenoid sinus.