Anti-basement membrane antibody disease is a rare disorder characterized by the presence of autoantibodies binding to the alveolar and glomerular basement membranes, and mediating both alveolar hemorrhage and acute glomerulonephritis. We retrospectively analyzed 28 cases of anti-basement membrane antibody disease with alveolar hemorrhage proven by bronchoalveolar lavage. The median age of patients at diagnosis was 23 years; 68% were male, 89% were active smokers, and 36% were exposed to some other inhaled agent. At diagnosis, 46% had predominant pulmonary involvement with normal initial serum creatinine. Lung function tests disclosed a restrictive ventilatory defect in 28% (n = 11) and hypoxemia (moderate in 29% and severe in 29%, n 2 1). Carbon monoxide transfer factor was elevated in only 25% (n = 12). Bronchoalveolar lavage was more sensitive than any other criterion for detecting alveolar hemorrhage. After onset of treatment. new hemoptysis or transient worsening of hypoxemia occurred in 29% but did not affect pulmonary outcome. In contrast, worsening of renal function occurred in 33% and adversely affected renal outcome. At last follow-up (median, 2.6 yr; n = 24), all patients were alive and a complete cure was achieved in 50%. Long-term dialysis or renal transplantation was required in 42%, and 8% had mild chronic renal insufficiency. Last chest X-ray was normal in all cases, and no patient had respiratory insufficiency. All patients with predominant pulmonary involvement at presentation maintained independent renal function. In summary, this cohort was characterized by frequent exposure to tobacco smoking and other inhaled agents, and a constantly favorable pulmonary outcome contrasting with frequent chronic renal failure. Renal outcome was excellent in the subgroup of patients with predominant pulmonary involvement.