To find the factors affecting reading agreement of pneumoconiotic findings of simple chest P-A films and to develop the definite quality assurance (Q.A) program for the reading of pneumoconiosis, I gathered the reading reports of the previously developed forty four chest films from nationwide thirty nine radiologists and compared those with the findings decided by the stepwise panel readings of the highly qualified eight radiologists. The reading agreement of profusion by complete or short classification was higher in the radiologists with sufficient reading experiences of pneumoconiosis during residency training. It was also higher in the radiologists with reference to ILO standard films or those working in the agencies for pneumoconiosis within one category of profusion by complete classification. Other factors were not related with the reading agreement of profusion. In small opacity and pleural thickening, there were not any consistent and meaningful findings between the reading agreement and radiologists' characteristics. From the above results, it is necessary to develop the Q.A program to improve the reading agreement of pneumoconiotic findings, especially small opacity and pleural lesions.