Giant cell arteritis (GCA) also is called temporal arteritis, cranial arteritis, and granulomatous arteritis. GCA is a systemic inflammatory vasculitis of unknown etiology that affects medium- and large-sized arteries. It is a disease of elderly persons and can result in a wide variety of systemic, neurologic, and ophthalmologic complications. Visual loss is one of the most significant causes of morbidity in GCA. Permanent visual impairment may occur in as many as 60% of patients. Newly recognized GCA should be considered a true neuro-ophthalmic emergency. Prompt treatment with steroids can prevent blindness and other vascular sequelae of GCA. Relationship with polymyalgia rheumatica A close relationship exists between GCA and polymyalgia rheumatica (PMR). Despite numerous reports associating these 2 disease entities, the precise nature for this association is poorly understood and currently unknown. However, it is evident that both conditions affect similar patient populations and frequently affect the same individual. Several authors have suggested that these 2 diseases are actually different stages of a single disease spectrum.