Vasculitis associated to antineutrophil cytoplasmic antibodies (ANCA) is a rare complication of therapy with antithyroid medication. They were mainly described in patients treated with propylthiouracil (PTU), carbimazole, methimazole and rarely by benzylthiouracil (Basden). We report a case of 12-years-old girl treated by benzylthiouracil for Grave's disease who developed after 2 years vasculitis associated with cutaneous involvement (generalized ulcer necrotic purpura) and glomerulonephritis with proteinuria of 24 hours at 26 mg/kg/day, microscopic hematuria and renal failure with creatinemia level at 135 micromol/l. The ANCA type antiMPO (myeloperoxidase) was positive. The histology study of the renal needle biopsy was in favour with focal necrotizing glomerulonephritisand crescents with different evolutive stages. The discontinuation of benzylthiouracil and the treatment by the corticoids involved a disappearance of cutaneous lesions, a negative result of proteinuria, a normalization of the renal function (creatinemia=84 micromol/l) and a disappearance of hematuria and ANCA. These results permitted to announce hypothesis that benzylthiouracil was implicated in development of vasculitis associated to ANCA.