The association between pleural plaques and asbestos exposure was investigated in a cross-sectional study of 951 male shipyard workers. Asbestos exposure was estimated by the men themselves and also by an expert panel whose judgment was based only on occupational title. The analysis was restricted to men who had had at least 20 years of exposure and who had not changed jobs during their period of employment in the shipyards. The results showed that there was a much closer correlation between the occurrence of pleural plaques and the men's own estimates of exposure than between the occurrence and the experts' estimates. Contrary to reports of other investigators, the authors found no association between smoking habits and the occurrence of pleural plaques (rate ratio = 1.0, chi 2 (1) = 0.3).