Inorganic dust inhalation diseases represent one of the most important chapters in respiratory medicine because of their diagnostic, therapeutic, legal, ecological and social implications. While, in fact, toxic substances inhalation may be easily related to particular occupations, it is more difficult to recognize the potential damage represented by occasional and fortuitous exposition due to pollution of one's living environment. The aim of this study was to suggest a useful investigative method for detecting the presence of mineral substances (dusts and fibers) in the lung in pulmonary fibrosis of uncertain origin. We used scanning electron microscopy (SEM) and semi-quantitative energy-dispersive x-ray microanalysis (EDXA) on broncholaveolar lavage (BAL) and sputum samples of 10 patients, all males, aged 41-66 years, smokers, affected by interstitial lung disease. Two subjects had a negative professional anamnesis while the other 8 declared a potential exposition to inorganic toxic dusts: 2 subjects were involved in the production of asbestos-containing building materials, 2 were miners, 1 a ceramic worker, and 3 insulating materials handlers. Data are reported on the detection of asbestos bodies, vitreous fibers and silica content of alveolar macrophages in BAL fluid.