Three recent cases of "mycotic aneurysm" or aneurysmal abscess of the carotid artery are described. Two cases involved the common carotid artery and occurred in heroin addicts, while the third patient had involvement of the internal carotid artery following a gunshot wound. Fortunately, no neurological sequel occurred in these patients following proximal ligation of the innominate, left common carotid, and left internal carotid arteries. Aneurysmal abscess of the carotid vessel should be suspected in any patient with an infected neck mass following heroin injection or penetrating trauma, and should be confirmed by arteriography. An early aggressive approach to treatment is recommended, including proximal arterial ligation without entering the infected hematoma.