With a long-term (1 and 4 months) introduction of an additional amount of edible fats (beef, hog fats, butter, sunflower seed oil) to intact and intratracheally quartz-dust laden sexually mature male rats an organ-specific reaction to the supply of fat, and in intact rats, also some peculiarities of the reaction depending upon the kind of the introduced fats, were discovered. An additional administration of fats to rats with developing silicosis tended to increase accumulation of lipids in the lungs and led to a higher content of oxyproline in the lungs and liver, which bears proof to an adverse effect produced by the introduced fats on the lipids metabolism and the processes of silicotic fibrogenesis.