Objetive To investigate the clinical characteristics, diagnosis, and treatment for diffuse alveolar hemorrhage. Methods The clinical data of 17 patients admitted to respiratory ICU with diffuse alveolar hemorrhage from July 1998 to May 2008 were reviewed. Results In the 17 cases, Wegener granulomatosis accounted for 6 cases, microscopic polyangiitis for 3 cases, systemic lupus erythematosis for 4 cases,mitral stenosis for 2 cases, and idiopathic pulmonary hemosiderosis for 1 cases. Clinical presentations included fever ( 76. 4% ) , hemoptysis( 47% ) , anaemia ( 100% ) , dyspnea ( 100% ) , hypoxaemia ( 100% ) ,and elevated total count of white blood cells ( 76. 4% ) . The titer of antineutrophil cytoplasmic antibody ( c-ANCA, p-ANCA) was 1∶( 46. 0 ±3. 7) , 1 ∶( 108. 0 ±16. 1) , respectively. Hemoglobin was ( 78. 0 ±2. 4) g/L. Bronchoalveolar lavage fluid presented with blood accounted for 35. 3% . Siderophages was found in all cases. Computed tomography showed areas of consolidation interspersed with areas of ground-glass attenuation and reticular interstitial opacities. Mortality was 29. 4% . Conclusions Diffuse alveolar hemorrhage is an acute life-threatening event. The clinical presentations of hemoptysis, dyspnea, and anaemia, and chest imaging studies provide clues to diagnosis of diffuse alveolar hemorrhage. Corticosteroids and immunosuppressive agents have proven effective in diffuse alveolar hemorrhage.