Introduction. Techniques that use growth factors to improve bone fragment consolidation and to treat the inflammatory and degenerative diseases of the musculoskeletal system have become very popular. Many researchers are actively searching for personification of this therapy and the reasons for delayed consolidation. The purpose of the study – to identify the biomarker for delayed bone consolidation.Materials and Methods. The study groups consisted of patients with high-energy tibia open fractures with normal (group 1) and with delayed (2nd group) consolidation of bone fragments. The enzymatic activity of platelet-derived growth factor (PDGF) in blood serum was studied after 7 days and in 1, 3 and 6 months after bone fragments reduction. Spectrophotometric technique (Specord-200) was used.Results. In patients with normal consolidation of bone fragments, the enzymatic activity of PDGF was statistically significantly higher in comparison with the group with delayed healing. At the same time, the highest activity was reported on day 7, and by third month it was becoming lower.Conclusion. Bone healing depends on PDGF enzymatic activity, besides significant differences on various stages of healing were observed. Further study the reasons for the PDGF enzymatic deficiency and its correction are of a great interest for reducing the timing of consolidation.