Excessive rate of scarring process impairs functional and aesthetic outlook. The causes and mechanisms of scar tissue hypertrophy have not been fully understood yet. The studies of dynamics of the scarring process allow optimization of approaches to conservative treatment at each stage of scar maturation. The aim of this study was to investigate the dynamics of structural changes and cellular responses in the scar tissue in children who suffered a severe thermal injury, as well as to optimize the diagnosis and treatment of scars. Material and Methods. We have examined and treated 217 children aged 2 to 15 years with cicatricial deformities that require multi-stage surgical treatment. Intraoperatively excised scar tissue and excess of skin autografts have been subjected to histological examination using morphometric and immune histochemical techniques. The findings were compared with the clinical presentation. Results. Compared to intact skin, the scar tissue within the first months after epithelialization displays increased levels of lymphocytes (by 8-9 times) and increased activity of macrophages (a 2-2.5-fold increase in CD68 expression), the main sources of cytokines. Hence, this period can be identified as the cytokine phase of scar development. The mechanism of apoptosis is impaired as activity of inflammatory cells increases (expression of an apoptosis marker p53 is reduced to 1.2-6.3, compared to the average level of 304.5 in the intact skin). Collagen synthesis in the scar tissue 4-6 months after wound epithelialization leads to development of venous outflow impairment. Therefore, this phase can be characterized as the venous-collagen phase. Later, collagen fibers compress the arterioles as well, leading to the arterial collagen phase. 1.5-2 years after the epithelialization the cellular activity declines and uniform constriction of vessels takes place in the scar tissue (i.e., the adaptation phase of the tissue to novel circulation conditions). The scar then reaches one of the stable forms: either hyperplastic or hypoplastic one. Conclusion. Prolonged activity of macrophages and lymphocytes in the scar disrupts the mechanism of apoptosis and stimulates fibroblast activity. Conservative treatment should be undertaken within the first months of scar development with allowance for the cellular processes occurring in scar tissue in each phase of the scarring process. This treatment can significantly improve the functional and aesthetic outcome.