PURPOSE: The purpose of this study was to evaluate the plain chest radiological findings of silicosis based on ILO 1980 Classification. METHODS AND MATERIALS: Author studied the plain chest films of 200 patients with silicosis in Taebaek district and silicotic lesions were classified bascd on ILO 1980 Classification. There were 196 males and 4 females among them(mean age;56.2 years). The mean duration of dust cxposurc was 18.8 years. Small and large opacities were classified according to their profusion, size and shape, and size category, respectively. Other associated findings were also analyzed. RESULTS: Amont 200 patients there were 153 cases of small opacities and 47 cases of large opacities. Category 2/2(21.6%) and q/q type(22.9%) were most common for small opacities, according to their profusion, size and shape. Category B is most common for large opacities, according to their size. Incidence and size of large opacities increased with duration of dust exposure. Associated findings of hilar eggshell calcifications(5.5%), calcified silicotic nodules(3.5%), active pulmonary tuberculosis(10.5%) and pleural abnormality(9.0%) were domonstrated, too. CONCLUSION: Plain chest radiological findings of silicosis were fine irrcgular and/or round small opacities in Ifie early phasc, but if advanced, large opacities of progressive massive fibrosis and focal cmphysematous appcared in the upper lung fields. Hilar lymphadenopathy and eggshell calcifications, active pulmonary tuberculosis, pleural thickening and calcifications could be associated.