High-resolution computed tomography (HRCT) may show parenchymal abnormalities in patients with normal or questionable findings on the chest radiograph; and because it provides an accurate assessment of the pattern and distribution of lung disease, it also improves the accuracy of the differential diagnosis. HRCT may be able to distinguish areas of potentially reversible disease from irreversible fibrosis and be a helpful guide to the optimal type and site of lung biopsy. This review summarizes the current indications for HRCT of the chest in the assessment of patients with acute lung disease, chronic infiltrative lung disease, pneumoconiosis, bronchiectasis, and emphysema.