In this report the clinical, laboratory, and histopathologic findings of nine children with polyarteritis are reviewed. All have had evidence of systemic involvement. Eight presented with fever, calf pain, erythematous painful nodules, and elevation of the acute-phase reactants. All were treated with prednisone at a dosage of 2 mg/kg/day. All of the children are alive but have had relapses at least once during the course of tapering the dosage of corticosteroids. Serious complications of disease have included myocardial infarction, hypertension, and impaired renal function.