Systemic vasculitis is a large group of heterogeneous diseases in which inflammation and destruction of blood vessels are the main manifestation, and a heterogeneous disease is a disease with different manifestations, because it affects multiple systems throughout the body. The clinical manifestations of systemic vasculitis are complex and varied because of the different types, sizes, and locations of the vessels involved and the internal organs they supply. The vessels themselves can be in stages of necrotic infarction or focal inflammation leading to subcutaneous hemorrhage. Systemic vasculitis is the most complex of the rheumatic diseases, often presenting with renal failure and a relatively aggressive prognosis. Systemic vasculitis can involve large, medium, and small blood vessels. The most predominant vasculitis of the large vessels is giant cell arteritis and macroarteritis, the most common vasculitis of intermediate size is polyarteritis nodosa and Kawasaki disease, and the most typical vasculitis of the small vessels is granulomatosis Wey, allergic granulomatous vasculitis, microscopic polyangiitis, allergic purpura, primary cryoglobulinemia, and cutaneous leukocytoclastic vasculitis. In summary, systemic vasculitis is a heterogeneous group of diseases in which inflammation or necrosis of the vessel wall is the main pathological change, which can lead to systemic vascular inflammation throughout the body or in one organ.