Cogan's syndrome is an autoimmune disease of unknown etiology, clinically manifested as non-syphilitic interstitial keratitis and audiovestibular symptoms. Increasing evidence suggests that Cogan's may be a systemic vasculitis. In this report, we review the vascular manifestations of Cogan's syndrome and report two cases of thoracoabdominal aortic aneurysm in patients with this disorder.