This article reviews the histopathological, clinical and immunological features of the arteritides. Based on these criteria, a classification scheme is proposed that includes infectious and non-infectious causes. Included in the non-infectious arteritides are: hypersensitivity vasculitis including serum sickness. Henoch-Schönlein purpura, mixed cryoglobulinaemia, hypocomplementaemia, drug and malignancy-associated vasculitis; arteritides of small and medium-sized arteries including polyarteritis nodosa, Kawasaki's disease, Wegener's granulomatosis, Churg-Strauss syndrome, necrotizing sarcoid granulomatosis, thromboangiitis obliterans (Buerger's disease) and localized forms of arteritis; arteritides involving large, medium and small-sized arteries which includes giant cell (temporal) arteritis, Takayasu's disease and arteritis of collagen-vascular disease (rheumatoid arthritis, rheumatic fever, Behçet's disease, Sjörgren's syndrome, systemic lupus erythematosis and systemic sclerosis.