On the basis of several reports, it could be established that glycogen a and protein 2 metabolism in muscle has a very fast turnover and also that it is under hormonal control. Nevertheless, even when it is known that the levels of circulating hormones are far from being constant s-6, there is a scarcity of available data concerning the spontaneous variation of muscle metabolites concentration during the 24 h period. This information might provide important clues for the choice of any experimental design schedule. Therefore, we considered it important to establish whether the content of substances such as DNA, total protein and glycogen in muscle tissue vary or remain unchanged during the 24 h period. The results obtained are presented in this paper.Facultad de Ciencias Médicas