Asbestosis shows peribronchiolar fibrosis with numerous asbestos bodies. Subpleural dots and curvilinear lines in HRCT are good indicators for the diagnosis of asbestosis. Asbestos-related lung cancer in Japanese Compensation System means lung cancer with asbestosis. Furthermore, pleural plaques and the content of asbestos bodies in the lung tissues with the term of occupational asbestos exposure are good indicators. Mesothelioma induced also by the low dense exposure to asbestos. For the definite diagnosis of mesothelioma, we need histological examination using biopsy and immunochemical staining for positive and negative markers. Benign asbestos pleurisy is diagnosed by cytological and biochemical examinations of pleural effusions and pleural biopsy. Diffuse pleural thickening depends on the extent of radiological findings and impairment of pulmonary function with occupational asbestos exposure.