Activity of vitamin E and its derivatives--alpha-tocopheryl quinone, its short chain analogue and alpha-tocopheryl acetate also containing short chain molecule were studied during chicken experimental muscular dystrophy. alpha-Tocopheryl quinone containing short chain molecule proved to be the most active substance; similarly to vitamin E the preparation increased the erythrocyte resistance to osmotic haemolysis, distinctly increased the content of ubiquinone and decreased concentration of ubichromenol in the chicken liver tissue as compared with E-deficient animals. At the same time, the content of ubiquinone was unaltered in skeletal muscles. The data obtained suggest that vitamin E could be effectively substituted by its derivatives for prevention an treatment of muscular dystrophy.