A 13-year old boy is described with painful joints, papular skinlaesions, malaise and haematuria. Impaired renal function and hypertension were found. In the past he frequently suffered of otitis media. Biopsies of kidney and skin lesions showed a vasculitis, furthermore the C-ANCA-titer (anti-neutrophil cytoplasm antibodies) was strongly elevated which justified the diagnosis Wegener's granulomatosis (WG). This disease is seldom seen in childhood. It is a necrotizing vasculitis with granulomas of mostly the respiratory tract and kidneys. Autoantibodies directed against intracellular antigens of neutrophils were first associated with vasculitis in 1982. Since 1988 two ANCA-subtypes have been recognized: C-ANCA and P-ANCA. The C-ANCA appear to be highly specific for diagnosis and follow-up of WG, and to differentiate of other forms of vasculitis (with P-ANCA). If children present with frequent and serious upper respiratory tract infections, with suspicion of a systemic disease it is important to perform the ANCA-test to differentiate between WG and other forms of vasculitis. The patient was treated with prednisone and cyclophosphamide, after which the symptoms and the ANCA-titer decreased.