Rats were administered with quartz dust intratracheally or subjected to chronic inhalation of the dust. Peroral overloading of rats with fat was shown to increase an accumulation of all lipid fractions in lungs and intensified silicotic fibrinogenesis. Similar alterations in lipid metabolism of lungs were observed in control animals maintained without the dust treatment at the same fatty diet; but these patterns were less distinct and were not accompanied by an increased collagene formation. Alterations in content of lipids in liver tissue and in blood did not depend on the dusting of lungs under fatty loading. Within the later period of inhalational dusting the increased accumulation of quartz was observed in lung tissue of rats maintained at fatty diet. The data obtained suggest that the recommended by some investigators increase in content of fats in miner's diet is not justified.