The frequency of Takayasu's arteritis (TA) has been estimated to be 2.9 cases per 1 million people, with a female preponderance, although female-to-male ratio varies from different geographic areas. A high frequency of haplotype A24-B52-DR2 has been found in Japanese patients, without this association in other populations. TA has a striking predilection for the aortic arch and its branches. Evidence favors an autoimmune pathogenesis. Segmental inflammation (active and inactive lesions) may coexist. Due to its enhanced resolution, magnetic resonance imaging and magnetic resonance angiography eventually will replace catheterization angiography. Mortality reduction with glucocorticoid treatment has not been firmly established.