Content of hydroxyproline, thyrosine, hexuronic acids, hexoses and dry weight of lungs were studied in animals with pneumoconiosis, caused by various agents: two types of silicosis, induced by crystalline and condensed modifications of silica, and anthracosis, caused by anthracite. The data obtained showed that in all the types of pneumoconiosis dry weight of defatted lungs was increased with simultaneous increase of hydroxyproline content in the tissue. The more pronounced alterations were observed in silicosis. In all the types of pneumoconiosis within the experimental period content of hexuronic acids was higher in impaired animals as compared with control ones; the increase in content of hexuronic acids preceded the accumulation of hydroxyproline. Content of hexoses and thyrosine was distinctly increased within 2 days, which apparently correlated with the processes of exudation. Then it was decreased and at the later steps of the impairment amount of hexoses and thyrosine was shown to increase with simultaneous accumulation of hydroxyproline. Dynamics of accumulation of non-collagen components of connective tissue in lungs depended upon the type of a dust to which the animals were exposed.