Background: Some biochemical indicators in patients with disorders of reparative osteogenesis were described in a sufficient number of studies, but the role of factors affecting the metabolism of bone tissue and the ways of their correction are not sufficiently studied .. For effective prediction of the course of reparative osteogenesis in fractures, it is important to identify early markers of impaired consolidation and, accordingly, its pathogenetic correction. Purpose: to determine biochemical indicators of the course of reparative osteogenesis in patients with multiple and monolocal fractures of the bones of the lower limb. Materials and Methods: 44 patients aged 23 to 47 years were examined. To assess the ratio and intensity of the processes of biosynthesis and breakdown of collagen, as the major structural protein of connective tissue, the following indicators were determined in the blood serum of patients: fractions of hydroxyproline, oxyproline, collagenase, cathepsin B, elastase, proteolysis-antielastase inhibitors. In addition, indicators of mineral metabolism were also determined in the blood serum of patients: the content of calcium, phosphorus, alkaline phosphatase activity. Results: A comparative analysis and comparison of the results of the biochemical examination of patients with closed tibial fractures and multiple fractures revealed that already at the beginning of the research, deviations from the norm in the indicators of both mineral and collagen metabolism were observed. Both groups of the patients are characterized by the presence of disturbances in the ratio between calcium and phosphorus, and in patients with multiple fractures - an increase in the level of alkaline phosphatase. The detected changes in the mineral metabolism in patients with multiple fractures had a more pronounced and intense character due to the multiple injuries and presence of a large number of destroyed cells in the first days after the injury. Conclusions: Indicators of the unfavorable course of reparative osteogenesis in patients with bone fractures are a decrease in the content of calcium/phosphorus in blood serum, an increase in the level of free oxyproline and collagenolytic enzymes (collagenase, elastase, cathepsin B). Besides, there is a decrease in the level of proteolysis inhibitors (antielastase, 2-macroglobulin) and a decrease in suspension stability and antioxidant activity, increase in blood fibrinolytic activity. Our findings justify the need for prophylactic drugs that improve reparative osteogenesis soon after the injury (within a month) in patients with multiple fractures in order to activate the processes of reparative regeneration.