The literature on asbestosis, the pneumoconiosis resulting from inhalation of asbestos (1332214) fibers, was reviewed. Occupational exposure to asbestos minerals constituted a major health hazard in the United States. Asbestos has over 3000 commercial uses, and occupational exposure occurs in the initial mining of the fibers, during the manufacture and use of asbestos containing products, and disposal of asbestos containing waste. The results of epidemiologic studies of the mortality and respiratory morbidity in asbestos exposed populations were summarized. Occupational exposure to asbestos was conclusively shown to be associated with asbestosis and respiratory cancer. The pathological findings in asbestosis and mesothelioma were described and illustrated. Asbestosis was characterized by diffuse interstitial fibrosis of the lung parenchyma, often accompanied by thickening of the visceral pleura, and sometimes calcification of the pleura. Mesothelioma, a rare tumor invariably associated with asbestos exposure, typically encased the lungs in a rubbery mass of ivory colored tissue, and commonly metastasized to local lymph nodes and the lung. Clinical manifestations of asbestosis included dyspnea on exertion, chronic cough, rales at the lung bases, and in advanced cases, finger clubbing. Radiographically, small irregular opacities distributed in the middle and lower lung zones were commonly observed. Pulmonary function tests usually demonstrated a restrictive impairment with reduced diffusing capacity. The authors conclude that asbestos exposure should be reduced to the lowest level possible in order to prevent asbestosis.