The complex physiology of iron metabolism has a long history of research, from the ferritin complex, which is among the oldest isolated proteins, to the last twenty years of upgrading to a complete picture with many participants whose role has still not been researched enough. Although ferritin complex interacts with all transition metals, its main purpose is to store iron in a cell. Iron, although the essential element, has to be precisely controlled so that the released does not cause the formation of reactive oxygen radicals (reactive oxygen species, ROS). Ferritin complex consists of 24 subunits forming a nanocage, i.e. protein sphere, and proteins which interact with it are of exceptional value in physiological processes of the cells using iron. Very early research on experimental animals found gender differences in the amount of iron in the liver and kidneys in favor of females, which was later associated to gender differences in the amount of ferritin in these organs. In this case, liver, i.e. hepatocytes, play a major role in storing iron in an organism, while kidneys are involved in its recycling. By using the new generation immunochemical methods in this work, sex and age differences in the expression of light and heavy subunits of ferritin in the liver of three months old and two years old experimental animals were followed. Detailed distribution of ferritin subunits inside the organ is obtained by immunohistochemistry, while differences in the expression of individual subunits are determined by western analysis. The results of immunochemical methods confirm that there are sex differences in both ferritin subunits and that age differences remain, while the amount of ferritin in both organs increases by indicating an increased amount of iron in them. Both ferritin subunits show a very similar distribution in the liver which is most pronounced in hepatocytes around the central vein. It is concluded that both ferritin subunits are expressed in the liver and show both sex and age differences which may be correlated with an increased amount of iron and thus with oxidative stress, which is crucial to the pathophysiological mechanisms of the aging process.