A comparison of the lipofuscin (aging pigment) content in four organs (liver, kidney, heart, brain) of young and adult rats, as well as in a suspension of hepatic mitochondria, was made. It was demonstrated that mitochondrial lipofuscin - mitolipofuscin, fluorescing in the blue region, makes the main contribution to hepatic lipofuscin. It is assumed that mitolipofuscin in other organs also makes a significant contribution. It is shown that accumulation of lipofuscin with age occurs in all organs of rats, but least of all in the brain. In addition to fluorescent lipofuscin, non-fluorescent protein aggregates are found in all organs, the largest number of which is found in the heart. Among them, a significant proportion is covalently cross-linked aggregates that are not destroyed by detergents. Their number also increases with age.