We studied the development of small irregular opacities and bilateral pleural thickening in a longitudinal study of 181 asbestos-cement workers. The relationships between the 32-yr risks of developing abnormalities and cumulative exposure to asbestos dust could be described with log-normal curves. Smokers had higher risks of both abnormalities than did nonsmokers. In this cohort, men leaving asbestos exposure had a risk of radiographic progression similar to men continuing in exposure, and men with abnormal radiographs had higher mortality rates than did men with normal ones.