SummaryThe pulmonary-renal syndrome is defined by the association of alveolar hemorrhage and rapidly progressive glomerulonephritis. Goodpasture syndrome and necrotizing vasculitides are the most frequent causes. New serologic markers are currently more rapidly available (anti-glomerular basement membrane-anti-GBM-and antineutrophil cytoplasmicantibodies-ANCA), allowing clinicians to identify and distinguish these 2 entities, and to hasten the initiation of a pulse therapy, now well standardized, which improves the outcome of patients. However, these 2 serologic markers have limitations so thai clinical assessment and renal biopsy remains essential in the diagnosis of pulmonary-renal syndrome. The authors propose an algorithmic approach for those confronted with such a condition.