The article is devoted to a pressing issue in regenerative medicine about the use of cellular products to stimulate reparative regeneration of bone defects. The article presents the results of a study of the structural characteristics of the regenerated rat femoral diaphysis with an induced defect using the secretome of multipotent mesenchymal stromal cells. White outbred rats (males, 120 g) were taken as the object of the study. The study material included femur samples taken on the 7th, 14th, 30th, 60th, 90th and 120th days. The work used methods of computed tomography, anatomical dissection and light microscopy. It has been shown that the use of the secretome of multipotent mesenchymal stromal cells in the early stages activates angiogenesis in the healing area. Against this background, stimulation of reparative osteogenesis occurs with better consolidation of the regenerate with the edges of the defect. In this case, the structure of the regenerate corresponds typical structure of the diaphysis: external and internal systems of bone plates and an osteon layer are observed. All this may indicate earlier remodeling of the regenerate, as well as restoration of the structural and functional characteristics of the bone. The data obtained can be used for further fundamental research in the field of regenerative medicine, as well as in clinical practice.