To investigate the prevalence of pneumoconiosis in Portland cement workers, a controlled cross-sectional survey was conducted. Chest radiographs of approximately 2640 Portland cement workers showed prevalence rates of about 1% for rounded and for irregular small opacities and about 2% for pleural abnormalities. After age and smoking adjustment, the overall prevalences were still significantly elevated over controls, but when examined separately by smoking status, the significant increases were confined to smokers. Although statistically significant, the prevalences were only elevated about 1% in cement workers, compared with controls. A statistically significant relationship with exposure was found for pleural abnormalities but not for rounded or irregular small opacities. Thus a weak association exists between pulmonary radiographic abnormalities and employment in US Portland cement plants, and there appears to be a dose-response relationship between exposure and pleural abnormalities.