[en] This paper determines the action of low (near-physiological) concentrations of alpha-tocopherol on the character of the gel-liquid crystal transition in a lipid bilayer containing free fatty acids. Fifty mM of K⁺-phosphate buffer was made up in D₂O and kept for several hours to enable substitution of H 1 by D 2, after which the buffer was dried and redissolved in D₂O. The graphs of temperature dependence of relative signal intensity of protons of methylene groups in liposomes of different composition are presented. It is shown that the stabilizing action of alpha-tocopherol on the phase state of the lipid bilayer of membranes is one of the mechanisms by which the recently demonstrated ability of alpha-tocopherol to protect biological membranes against the injurious action of free fatty acids, through the formation of complexes of alpha-tocopherol with fatty acides, may be effected