Takayasu's arteritis is a worldwide entity that requires astuteness for early diagnosis. The challenge for the practicing physician is to document active disease, not only to justify immunosuppressive therapy but also to determine the appropriate timing for surgical intervention. No single laboratory assay or imaging modality establishes disease activity, though T2-weighted magnetic resonance imaging, magnetic resonance angiography, and spiral computed tomographic angiography have shown potential in identifying acute inflammatory changes within the vessel wall. Treatment consists primarily of glucocorticoids, but cytotoxic agents such as methotrexate and cyclophosphamide may be added to treat recalcitrant disease. New immunomodulating agents such as leflunomide and tumor necrosis factor inhibitors require further study before they can be added to the treatment armamentarium.