Typical Cogan syndrome (CS) is a disease of young adults consisting of flares of interstitial keratitis (IK) and sudden onset of Ménière-like attacks. The prognosis of typical CS is excellent with life-threatening aortic insufficiency (AI) developing in only 10% of reported cases. Serious systemic necrotizing vasculitis (SNV) rarely, if ever, complicates typical CS. Atypical S (vestibuloauditory dysfunction with types of inflammatory eye disease other than IK) frequently overlaps other defined rheumatologic syndromes, is associated with vasculitis in 21% of cases, and carries a less favorable prognosis than typical CS. Topical ocular corticosteroids can usually control IK, and a short trial of systemic corticosteroids is warranted as soon as possible after the onset of hearing loss. SNV should be treated initially with prednisone and may also require the administration of cytotoxic agents, while aortitis and AI can be controlled with the administration of prednisone and surgical replacement of the aortic valve.