Necrotizing and crescentic glomerulonephritis without immunoglobulin deposits (also called pauci-immune glomerulonephritis) is the cause of approximately 50 percent of acute renal failures of glomerular origin. Our study, based on 40 case-records selected on histological criteria, and on data from the literature, shows that in most cases, if not all, this type of glomerulonephritis is part of a wider systemic vasculitis which predominantly affects the glomerular capillaries. Anti-neutrophil cytoplasm antibodies are detected in three-quarters of the cases, with a specific distribution that varies according to the clinical features. In spite of the patients' age (mean: 62 years), the severity of glomerular lesions and the extra-renal diffusion of the disease, 60 percent of these patients can be cured and recover a normal, or at least acceptable renal function, provided the corticosteroid and sometimes immunosuppressive therapy is initiated at an early stage.