The effect of water soluble tocopherol forms (dipotassium salt d,l-alpha-tocopheryl-phosphate) on lipid peroxidation induced by oxygen in membranes of human erythrocytes has been studied. An erythrocyte was considered as a structure reflecting the state of plasmatic membranes of organs and tissues. It has been established that this substance doses optimum for membrane protection against lipid peroxidation are not in excess of 1.5-5.0 mg per 1 kg of human body mass; the dose by an order higher may exert a toxic effect.