A chest x-ray film screening program for coal workers was described, and two examples of epidemiological analyses using data from the screening program to evaluate the effectiveness of the coal dust standard of 2mg/m3 were presented. A consensus film reading was derived by using the median or middle reading of three or more readers for every x-ray. Temporal variation, film quality, technical differences, as well as differences in individuals, all may contribute to variability. Two analyses to evaluate the effectiveness of the coal dust standard were completed using only miners who had worked entirely under the mandated dust standard. The two analyses are: determination of coal workers' pneumoconiosis (CWP) prevalence; and determination of the progression of CWP among miners participating in both Rounds 1 and 3 of the x-ray film screening program. In the prevalence study, prevalence for the group with 0 to 9 years tenure was 0.94 percent. When converted to epidemiological readings, the prevalences were rates of CWP were not in excess of expected levels and did not differ significantly from those observed in non dust exposed workers. The authors conclude that prevalence and progression rates of CWP for miners are in agreement with data from published epidemiological analyses. Low participation of working miners in the screening program, nonuniformity of method, short follow up period and inadequate training and education of coal miners are problems that need future attention.