High resolution CT (HRCT) can image the fine structures of the lung parenchyma and the pleura. Analysis of supine and prone HRCT scans in 300 patients with asbestos exposure shows that asbestosis is characterized the following findings; (1) parenchymal bands, (2) increased interlobular septa, (3) increased intralobular core structures, (4) subpleural lines, and (5) dependent opacity. Pleural disease is well displayed on HRCT scans. Correlated studies with whole lung sections confirm the HRCT findings. Masses in asbestosis may be benign or malignant, and CT helps in their differentiation. HRCT correlates well with radiographic and clinical criteria for asbestosis and is more sensitive than either in detecting abnormalities.