Vasculitic syndromes comprise a heterogeneous group of disorders sharing the hystopathologic features of inflammation and necrosis in blood vessels. Their clinical expression depends on site, type and size of the involved vessels and severity of the associated inflammatory symptoms. Classification of vasculitides based on the size of the affected vessels is the most widely used in children. Many different vasculitides with indistinguishable clinical presentation have very different prognosis and treatments. Among the primary systemic non-granulomatous vasculitides of medium-sized vessels in pediatrics we have to consider Kawasaki disease and among the small-sized ones Henoch-Schönlein purpura, which is the most frequent vasculitis of the pediatric age and is characterized by vascular deposition of IgA-dominant immune complexes. Accurate diagnosis is the mainstay for the definition of the best therapeutical proposal, though therapies available result largely empirical and based on trials with limited numbers of pediatric patients.