The International Labour Organisation (ILO) classification of radiographs of pneumoconioses was developed to limit variation in classification of parenchymal abnormalities. In this study the manner in which chest radiographs were interpreted in 134 investigations reported in four peer reviewed journals during the five year period 1985-90 was examined. The approach for applying the ILO system was poorly described in most studies. For example, of 86 investigations using more than one reader, 66.3% described the method of reconciliation, but methods were not consistent among investigations. Our results indicate a number of potential problems in application of the ILO system, and gaps in existing recommendations that should be considered.