Asbestos-related disease in a group of 153 plumbers and pipefitters employed in building construction was assessed by means of a cross-sectional prevalence study. Study methods were medical questionnaire, spirometry, measurement of diffusing capacity, physical examination of the chest, and chest roentgenogram. The major finding was bilateral pleural thickening in 28 (18.3%) of the participants. Unilateral pleural thickening was found in 12 subjects (7.8%). Small irregular opacities of profusion 1/0 or greater were found in 12 subjects (7.8%). Bilateral pleural thickening was associated with both age and time since first asbestos exposure, while unilateral pleural thickening was associated only with age. Decreases in forced vital capacity (percent predicted) were associated with duration of exposure. The most prevalent abnormality found was bilateral pleural thickening, which is more specific for asbestos exposure than is unilateral pleural thickening.