The "pulmorenal syndrome" is a clinically defined syndrome under which one summarises disease entities with acute renal failure due to acute glomerulonephritis and alveolar lung hemorrhage. Wegener's granulomatosis, other inflammatory renal diseases and Goodpasture's syndrome are the most frequent causes of this syndrome. The physical examination and histological examination, mostly of a kidney biopsy, represent the mainstay of securing the diagnosis. The diagnosis is completed by serological testing for autoantibodies. The therapy is determined by the underlying disease. Plasmaspheresis is always performed when alveolar hemorrhage is present, and in most cases where the patient presents with the need for immediate dialysis. An immunosuppressive therapy is determined by the underlying disease.