The authors have examined the time course of lipid peroxidation processes and the levels of total lipids in red cell membranes and blood plasma of diabetics administered alpha-tocoferol acetate. Patients with medium-severe diabetes of the first and second types were divided into 2 groups. Group 1 patients were administered only traditional sugar-reducing treatment, in Group 2 alpha-tocoferol acetate in a daily dose 300 mg was added to such therapy. Similar examinations were carried out in both the groups before and after the treatment. Lipid peroxidation levels and the content of total lipids were found significantly increased in the cellular membranes and blood plasma of Group 2 patients, whereas in Group 1 no changes of this kind were detected. Therapy with alpha-tocoferol acetate normalized lipid peroxidation processes in the red cell membranes and the total lipid content in the blood plasma reduced the blood plasma level of lipid peroxidation products and the content of total lipids in red cell membranes. These results permit a conclusion on the favorable effect of alpha-tocoferol acetate on blood plasma lipid peroxidation and total lipid levels in diabetics.