We compared results of classification of 576 selected chest radiographs of workers in Chinese tungsten and coal mines according to the standard Chinese classification system and the latest (1980) International Labour Office's revision of the International Classification of Radiographs of Pneumoconioses. The Chinese ‘suspect pneumoconiosis’ category accorded closely with ILO profusion category 0/1 for small opacities, and nearly all those classified in the Chinese system as showing some definite nodular opacities in only the middle or lower zones of the lung (Grade I) were classified into category 1 in the ILO ‘short’ classificalion. But the Chinese Grade II, which describes the most extensive signs of small opacities, covered a wide range of profusion on the ILO scale, comprising 48% in category 1, 46% in category 2 and 6% in category 3. There was good agreement between the two systems in identifying radiographs with large opacities. Suggestions are made to elaborate the Chinese classification system. The aim is to increase the range of appearances that are classifiable and assist international comparisons with categories defined by the ILO scheme, while still retaining the basic elements of the traditional Chinese diagnostic categories.