A critical reappraisal of the clinical, arteriographic, and pathologic features of Takayasu's arteritis and so-called congenital aortic coarctations at atypical sites is presented. It is concluded that as an isolated cardiovascular abnormality, cases of atypical congenital coarctations of the descending thoracic and abdominal aorta are probably rare. The majority of atypical aortic coarctations previously reported in the United States and Europe as congenital lesions apparently represent unrecognized cases of Takayasu's arteritis.