Concentration of vitamin E (alpha-tocopherol) was studied in liver, kidney, heart, and skeletal muscle of 12 mammalian species. 9 of them inhabiting under natural conditions, while 3 being farm-bred. In most of the species the highest tocopherol distribution and level have been revealed, including those in taxonomically close species. These differences seem to be due to ecological peculiarities of the animals. The obtained results allow considering as one of factors of maintenance of the natural antioxidant system at the steady level.