This paper shows that the exogenous delta-sleep-inducing peptide (DSIP) injected subcutaneously into rats at an age of 2-24 months of postnatal development in a dose of 100 mg/kg of animal body weight in courses for five consecutive days each month has a hepatoprotective effect. DSIP does not affect the functional activity of the pancreas and is not involved in the regulation of calcium homeostasis in the physiological aging of an organism. © 2013 Pleiades Publishing, Ltd.