Antioxidant system (AOS) is the most important unit of the general biological defense system. In assessing its state the choice of adequate, stable and sensitive indicators is important to determine the products of lipid peroxidation (LPO) and antioxidant defense enzyme complex. Antioxidant Index (AOI) is based on detecting blood and erythrocyte lipid peroxidation products such as malondialdehyde, diene conjugates of polyunsaturated fatty acids, and assessing the activity of antioxidant enzymes (i.e. superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase) in erythrocyte membranes. The aim of this work was to evaluate the role of AOS in the mechanism of blood oxidative homeostasis in Soviet Chinchilla rabbits (males and females) during different periods of ontogeny. Studies were performed in bioclinic on 10 rabbits.