The workers of an iron foundry were exposed to air pollution, which after some time of exposure results in lung fibrosis among some workers. The diagnosis of pneumoconiosis in workers of an iron foundry is based mainly on the radiological findings among workers exposed to the dust causing lung fibrosis. However, on radiograms many parenchymal structures overlap, which limits sensitivity and specificity to the method. Difficulties in accurate interpretation of conventional radiograms in silicosis also result from their relatively low resolution. The purpose of the present study was to assess the value and usefulness of high resolution computed tomography in the diagnostics of nodular changes in foundry workers' pneumoconiosis, compared to conventional radiography. The study group consisted of 64 iron foundry workers in whom silicosis had been recognized. The average age of the group was 51years and the mean silica exposure time was 23 years. Chest radiograms with hard X-rays were taken at the maximal inspiration phase. For the HRCT examination the Siemens Somatom ART apparatus was used, equipped with a 512 x 512 pixels reconstruction matrix and a special programme for high resolution algorithm imagere construction. In our material, consistency of results for conventional radiography and HRCT in revealing the presence of nodules was high. A statistically significant increase in detectability of intralobular nodules and peripheral nodules localized under the pleura was observed. The increase in detectability of cavernous, calcified nodules and those in the upper pulmonary fields obtained from computed tomography, however, was not statistically significant. High resolution computed tomography provides significanta dditional information in patients with foundry workers' pneumoconiosis.