Behçet's disease (BD) is a systemic vasculitis of arterial and venous vessels of any size, involving young patients (from 15 to 45 years). BD significantly increases morbidity and mortality. Therapeutic management of BD depends on the clinical presentation and organ involved. Although colchicine, nonsteroidal antiinflammatory agents and topical treatments are often sufficient for mucocutaneous and joint involvement, more aggressive approach with immunosuppressive agents is warranted for severe manifestations. Early recognition and vigorous use of immunosuppressives with high dose steroids have changed the prognosis of patients with severe BD. BD is a severe systemic vasculitis leading to blindness in up to 20% at 4 years and a 5-year mortality rate of 15% in patients with major vessel or neurological involvement. Cyclophosphamide has been used for life-threatening BD for 40 years. However, the outcome of severe complications of BD is poor. The European League Against Rheumatism (EULAR) recommendation for the management of BD advocated cyclophosphamide plus glucocorticoids for life-threatening manifestations (i.e neurological and/or major vessel involvement). TNFa antagonists have been used with success in severe and/or resistant cases. In addition, the incidence of blindness in BD has been dramatically reduced in the recent years with the use of anti-TNF. However, there is no firm evidence or randomized controlled trials directly addressing the best induction immunosuppressive therapy in severe BD manifestations. We therefore aimed to assess the best induction therapy in severe and difficult to treat BD patients. We hypothesize that up to 70% of the patients with life-threatening manifestations of BD receiving these compounds [anti-TNFa or cyclophosphamide] will achieve a complete remission of BD at 6 months and with less than 0.1 mg/kg/day of prednisone.