A 17-year-old man was admitted to our hospital because of exertional dyspnea, fever, and hemoptysis. Chest X-ray films disclosed diffuse alveolar infiltrates and patchy shadows in both lungs. Laboratory data included a hemoglobin level of 6.7 g/dl and white blood cell count of 8,100/microliter. Urinalysis revealed microscopic hematuria with RBC cast. Bronchoalveolar lavage fluid from the right middle lobe bronchus was bloody. Anti-GBM antibodies were detected at low levels in serum (10 EU/ml) by ELISA procedures. Renal and lung biopsies were performed. Immunofluorescent studies revealed linear deposits of IgG along glomerular basement membrane of the kidney, but not in alveolar walls of the lung. This case fulfilled the criteria for Goodpasture's syndrome. The patient was treated with methylprednisolone (1,000 mg/day, for 3 days) and plasma exchange (for 2 days), and demonstrated a dramatic improvement in his clinical condition and chest X-ray findings. We were unable to identify autoantibodies to the NC domain of the alpha 3 chain of type IV collagen. Another conformational epitope may play a role in the disease.