Introduction. The processes of physiological regeneration of cells in the body (apoptosis, proliferation, differentiation) are influenced by various factors, including medications. Experiments at the cellular level are widely used In scientific research and preclinical trials of potential drugs. It includs the use of organotypic tissue culture that preserves all the variety of cell types inherent in the tissues of various organs. The aim of the work is a comparative study of the effect of the KED peptide on the growth of organotypic tissue cultures of mesodermal genesis in young and old rats. Material and methods of investigation. There are experiments in organotypic culture of skin, cartilage and spleen of young (3 month) and old (24 month) rats of Wistar line for study the KED peptide activity. Tissue explants were cultured in a CO2 incubator for 3 days. The growth of tissue explants in organotypic culture was studied in vivo using a phase contrast microscope. The area index of the explant growth zone was calculated as the ratio of the area of the entire explant, including the peripheral growth zone, to the area of the central zone, and expressed in % relative to the control. Results. It was shown, that geroprotector KED peptide in the concentration 0.05 ng/ml stimulates the growth of organotypic culture of mesodermal genesis tissues. The most stimulation was observed in skin, cartilage and spleen of young, as compared to old rats. Thus, the method of the organotypic tissue culture is effective for the investigation of biogical active substances, which regulate the regeneration processes in tissues of the organism. This method resolves to detect the effective concentrations of these substances. It is possible to create on base of these data for the formation of the drug substances for increase of the regeneration processes by tissues pathology, including the age pathology. Conclusion. KED peptide is a perspective potential geroprotector for the correction of age pathology of skin and supporting-motor apparatus.