Aneurysms of the petrous portion of the internal carotid artery are rare lesions. One case is reported here and 18 others have been found in the literature. These lesions usually arise in young men who present with auditory dysfunction. The aneurysm is usually discovered as a pulsating purple mass in the middle ear and mistaken for a glomus jugulare tumor. A definitive diagnosis can be made by carotid angiography. Subtraction techniques are very helpful. Carotid ligation or trapping is the treatment of choice.