A comparative study of the ability of high speed, high resolution computed tomography and chest X-rays to detect abnormalities in persons with pneumoconioses was conducted. The study group consisted of 108 patients with silicosis, asbestosis, welder's lung, foundry worker's lung, or activated carbon pneumoconiosis, the radiographic profusions of which ranged from 0/1 to 3/3 on the 1980 International Labour Organization scale. High speed, high resolution X-ray computed tomographic scans of the lungs were performed. Their ability to detect bullae, blebs, pulmonary emphysema, honeycombing, pneumothorax, pleural thickening and plaque formation, coalescence of nodules, and egg shell calcifications was compared with that of posterior/anterior chest X-rays. The tomographic scans detected 24 cases of bullae, 28 of blebs, 13 of pulmonary emphysema, nine of honeycombing, three of pneumothorax, 16 of pleural thickening and plaque formation, four of nodular coalescence, and 14 of egg shell calcification. The X-rays detected three cases of bullae, two of blebbing, none of pulmonary emphysema, five of honeycombing, two of pneumothorax, five of pleural thickening and plaque formation, two of nodular coalescence, and seven of egg shell calcification. The authors conclude that high speed, high resolution computed tomography has high detectability for abnormalities of the pulmonary parenchyma or interstitium and pleura. Computed tomography should greatly increase the sensitivity of imaging techniques for detecting pneumoconioses.