The workers of an iron foundry were exposed to air pollution, which aftersome time of exposure results in lung fibrosis among some workers. The diagnosis of pneumoconiosis inworkers of an iron foundry is based mainly on the radiological findings among workers exposed to thedust causing lung fibrosis. However, on radiograms many parenchymal structures overlap, which limitssensitivity and specificity to the method. Difficulties in accurate interpretation of conventional radiogramsin silicosis also result from their relatively low resolution. The purpose of the present study was toassess the value and usefulness of high resolution computed tomography in the diagnostics of nodularchanges in foundry workers' pneumoconiosis, compared to conventional radiography. The study group consistedof 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 atthe maximal inspiration phase. For the HRCT examination the Siemens Somatom ART apparatus was used, equippedwith a 512 x 512 pixels reconstruction matrix and a special programme for high resolution algorithm imagereconstruction. In our material, consistency of results for conventional radiography and HRCT in revealingthe presence of nodules was high. A statistically significant increase in detectability of intralobularnodules and peripheral nodules localized under the pleura was observed. The increase in detectabilityof cavernous, calcified nodules and those in the upper pulmonary fields obtained from computed tomography,however, was not statistically significant. High resolution computed tomography provides significantadditional information in patients with foundry workers' pneumoconiosis.