To evaluate the 67Ga lung uptake as an indicator of inflammatory activity in asbestosis, we obtained 67Ga lung scans in 58 long-term asbestos workers. The 67Ga localized excessively in the lungs of 17 of the 21 workers with asbestosis. Among workers without sufficient criteria for the diagnosis of asbestosis, the 67Ga scan index was significantly increased in 43% (16 of 37). Among the 16 with positive 67Ga scan, abnormal pressure-volume curve and/or gas exchange data were found in 87%, whereas in the 21 workers with negative 67Ga scan, similar abnormalities were found in only 29%. In the sheep model of the disease, bronchoalveolar analysis after 67Ga scan demonstrated that the excessive uptake of 67Ga in asbestosis is caused by enhanced serum protein leakage and macrophage accumulation in the lung. Thus, 67Ga scanning in asbestos workers may be a useful indicator of early lung damage.