Behcet's syndrome can involve all sizes and kinds of blood vessels. There is an association between arterial involvement and venous thrombosis. Pulmonary arterial aneurysms and neurological involvement have a definite influence on mortality. Male sex and young age are indicators of a more severe disease course. Immunosuppressive treatment early in the disease may affect the long term prognosis favourably. Patients with familiar Mediterranean fever may develop manifestations of vasculitis. The most common associations are with Schonlein-Henoch purpura and polyarteritis nodosa. In some patients the diagnosis of vasculitis precedes that of familial Mediterranean fever. Kawasaki disease, although rare, can be seen in adults. The coronary sequela of childhood disease can affect the prognosis later in life. Many conditions, like myxoma, cholesterol embolism, and calciphylaxis may mimic vasculitic syndromes. These conditions should always be kept in mind because their pathophysiology and treatment are different from true vasculitides.