The therapeutic strategy in systemic necrotizing vasculitides comprises steroids and, in severe forms, immunosuppressants like cyclophosphamide. A combination of steroids and immunosuppressants should be proposed for severe forms only. When factors of poor prognosis are absent, steroids alone can be prescribed. When vasculitides are related to viral infection, a specific approach is needed that comprises a combination of antiviral treatments and plasma exchanges. In Wegener's granulomatosis, the combination of steroids and cyclophosphamide, either oral or pulse, should be prescribed. A maintenance treatment with azathioprine or methotrexate is recommended. Alternative treatments using other immunosuppressants or immunomodulating agents can be prescribed in the case of relapse or in patients who do not respond to conventional treatments. The different therapeutic modalities should also be adapted to the patient's age and general condition.