Data concerning the study of interrelationship between the mitotic activity of the corneal epithelium and the basal metabolic rate in mice are presented in this paper. Mice which were kept in individual cages and several mice kept together in one cage were used in this experiment. Oxygen consumption in mice kept in individual cages is permanently increased. The increased number of mitoses in the corneal epithelium corresponds to the rise in oxygen consumption by these animals. Increased number of mitoses is due to a more or less proportional increase of all stages of division. The authors came to the conclusion that the relative length of the interphase in the life cycle of a cell is decreased in animals with high basal metabolic rate.