Pleural plaques can be caused by asbestos exposure, but their predictive value in diagnosing pulmonary asbestosis is uncertain. Similarly, although high-resolution computed tomography (HRCT) can accurately detect parenchymal lung lesions, its ability to detect asbestosis is unknown. In a test of the predictive value of pleural plaques and HRCT, lungs of 29 autopsied patients with bilateral parietal pleural plaques were compared with lungs from 29 age- and sex-matched controls without pleural plaques. Significantly more of the patients with pleural plaques had histories of asbestos exposure (P less than 0.01). One lung from each patient was inflation fixed and air dried. HRCT of the lungs did not show significantly more thickening, lines, or densities in patients with pleural plaques than did controls; and HRCT did not predict a significantly greater likelihood of asbestos-related parenchymal disease in the study group. Gross and histologic examinations showed no significant intergroup differences in the frequency or severity of several forms of emphysema and fibrosis. Average asbestos fiber counts were not significantly higher in the lungs with pleural plaques. We conclude that pleural plaques do not predict asbestosis, and that high-resolution computed tomography accurately detects interstitial and parenchymal lung disease but cannot reliably diagnose asbestosis.