The systemic necrotizing vasculitis (SNV) are a subset of vasculitis with significant morbidity and mortality (2). The SNV are Wegener's granulomatosis, allergic angiitis and granulomatosis (AAG) (also known as Churg-Strauss syndrome), polyarteritis nodosum (PAN), microscopic polyangiitis (MPA), and overlap syndrome. In spite of modern therapeutic immune suppressive agents, there remains a not inconsequential morbidity and mortality associated with SNV. The current standard therapy for SNV is chronic oral cyclophosphamide (1-3 mg/kg/day) and corticosteroids (3-6). Transplant doses of cyclophosphamide at 200 mg/kg infused over 4 days is the most common worldwide transplant regimen for systemic lupus erythematosus (SLE) (7). Like SLE, SNV are cyclophosphamide responsive disease. We, therefore, propose a trial of high dose cyclophosphamide with anti-thymocyte globulin (ATG) for patients with SNV.