The clinical observation, the work history, the analysis of pulmonary function tests and, mainly, the conventional x-ray chest radiograms have represented, til now, the diagnostic basis for pneumoconiosis (silicosis, mixed dust pneumoconiosis, asbestosis). Recently, the high resolution chest tomography (HRCT) has been introduced into the diagnostic procedures: such method seems to have its main application in the assessment of incipient clinical pictures of pneumoconiosis, particularly when characterized by normal pulmonary function tests. 75 silica- and mixed dust exposed workers were submitted to both radiologic methods. The great majority of them had already been recognized to be affected by asbestosis. The statistical analysis (Cohen K) showed a satisfactory agreement between radiographic and tomographic I.L.O. classes. However, high resolution tomography appeared to be more accurate in the assessment of less severe clinical pictures. In conclusion, we underline the importance of high resolution chest tomography in the evaluation of individual clinical cases, particularly when forensic problems are involved.