It has been researched the relationship between diet containing different amounts of protein, carbohydrates and fats on the immune status of the aged rats. It has shown, that the diet with mainly containing proteins normalizes rate of immune status. The diet mostly based on carbohydrates, does not change the performance of T-lymphocytes, but has allergic effect on the body, increasing the performance of immunoglobulins. The diet rich in fats have a positive dynamics on the T-lymphocytes rates, but due to the development of fatty liver disease it has a negative effect on the amounts of immunoglobulins.