PURPOSE: To describe the chest radiographic and CT findings of diffuse pulmonary hemorrhage. MATERIALS AND METHODS: Two radiologists retrospectively analysed the chest radiographic and CT findings of six patients withdiffuse pulmonary hemorrhage. Using open lung biopsy (n=2) and transbronchial lung biopsy or bronchoalveolarlavage (n=4), diagnosis was based on the presence of hemosiderin-laden macrophage or intra-alveolar hemorrhage.Underlying diseases were Wegener's granulomatosis (n=2), antiphospholipid antibody syndrome (n=2),Henoch-Schonlein purpura (n=1), and idopathic pulmonary hemosiderosis (n=1). In all patients, sequential chestradiographs, obtained during a one to six-month period, were available. HRCT scans were obtained in five patients,and conventional CT scans in one. Follow-up HRCT scans were obtained in two. We also analyzed the patterns ofinvolvement, distribution and sequential changes in the pulmonary abnormalities seen on chest radiographs and CTscans. RESULTS: Chest radiographs showed multifocal patchy consolidation (n=6), ground-glass opacity (n=3), andmultiple granular or nodular opacity (n=3). These lesions were intermingled in five patients, while in one therewas consolidation only. Sequential chest radiographs demonstrated the improvement of initial pulmonaryabnormalities and appearance of new lesions elsewhere within 5-6 days, though within 7-25 (average, 13) days,these had almost normalized. HRCT scans showed patchy consolidation (n=5), multiple patchy ground-glass opacity(n=5), or ill-defined air space nodules (n=4). These lesions were intermingled in five patients, and in one,ground-glass opacity only was noted. In two patients there were interlobular septal thickening and intralobularreticular opacity. The distribution of these abnormalities was almost always bilateral, diffuse with no zonalpredominancy , and spared the apex of the lung and subpleural region were less affected. CONCLUSION: Althoughchest radiographic and CT findings of diffuse pulmonary hemorrhage are nonspecific, sequential changes inbilateral multifocal patchy consolidation and ground-glass opacity, accompanied by clinical symptoms such ashemoptysis or anemia, may be helpful in the diagnosis of diffuse pulmonary hemorrhage.