A cross sectional study of pneumoconiosis occurrence in United States (US) Portland cement workers was conducted. Standard postero/anterior chest X-rays obtained from 2,736 workers employed at 16 Portland cement factories in the US and 1,418 blue collar workers from food production, synthetic textiles, and electrical equipment factories in North Carolina (controls) were read for opacities using 1971 International Labor Organization (ILO) criteria. Subjects were interviewed by questionnaire to obtain information on demographics, occupational history, and smoking habits. Breathing zone samples were collected and analyzed for total and respirable dust and respirable crystalline silica (14808607) and asbestos (1332214) dust. Most of the subjects (95.1% of the cement workers and 50.1% of the controls) were male. The mean ages of the cement workers and controls were 40.9 and 33.9 years old, respectively. Approximately 43.6% of cement workers and 48.8% of controls were smokers and 24.3% of cement workers and 36.2% of controls never smoked. Total dust exposures of cement workers varied from 0.01 to 78.61mg/m3, geometric mean (GM) of 2.90mg/m3. Respirable dust exposures ranged from 0.01 to 4.622mg/m3, GM of 0.57mg/m3. Crystalline silica was detected in 14.4% of the respirable dust sample at concentrations of 0.012 to 5.084mg/m3, median of 0.079mg/m3. Asbestos was not detected in any samples. Cement workers had prevalence rates of small rounded opacities of ILO category one or greater and small irregular opacities of category one or greater of 0.79 and 1.10%, respectively. Approximately 1.59% of the cement workers had pleural abnormalities. Rounded and irregular opacities and pleural abnormalities prevalence rates in cement workers yielded odds ratios of 4.67, 6.45, and 5.03, respectively, when compared to controls and after adjusting for age and smoking. When examined according to smoking status, rounded and irregular opacities and pleural abnormality prevalence rates were significantly elevated only among cement workers who currently smoked, 1.1, 1.8, and 2.9% compared to the controls, 0.0, 0.1, and 0.3%, respectively. After adjusting for age and years of smoking, only the risk for pleural abnormalities was still significantly elevated. The authors conclude that a weak association exists between pulmonary radiographic abnormalities and employment in the US Portland cement industry, mainly in smokers.