Peculiarities of carbohydrate, lipid, amino acid nucleotide metabolism, of the tricarboxylic acid cycle functioning and of the oxidative phosphorylation have been studied in man and animals under conditions of changes in the acid-base equilibrium (ABE) state in the organism. The results of studies are analyzed and generalized. Strictly defined peculiarities of changes in the mentioned aspects of metabolism depending on the ABE state in the organism are revealed. Basing on a new interpretation of the experimental data and detected regularities in the metabolism, the author has drawn a conclusion on the existence of the previously unknown system of acid-base homeostasis in tissues. The physiological sense of this system functioning is the regulation of the intracellular acid-base equilibrium stability. The regulation mechanisms promoting functioning of this system are discussed. The system is shown to be of great applied significance for improvement of methods to cure a number of human and animal diseases as well as for an increase of the productivity of animals.