Medical news of north caucasus 2017. Vоl. 12. iss. 3 273 C hronic constipation in childhood is a serious and an unsolved problem [3, 4, 11]. The functional infringements of the colon motor action are revealed after the first year of life, gradually, during several years, constipations assume a steady character. According to the literature data, critical conditions often appear and they lead to the lethal result, even in case of using modern intensive therapy strategies [5, 8]. At the same time the depth of acid-base changes and the increase of a blood lactate level correlate with the heaviness of the disease, shock development and organ system insufficiency causing lethality [10, 12]. Thus J. Aduen and co-authors (1994) proved that at the lactate increase to 2.7 mmol/L the vital functions infringements are not observed. But at achieving the level to 4.0 mmol/L the lethality reaches 50 %, at the increase to 6.0 mmol/L is 90 %. The other important factor in progressing of toxic complications development is the infringement of colon microbiocoenosis, colonic dysbiosis, supporting the hemostasis violation not only in the colon, but in the whole organism. Thus the acid-base balance violation and colonic dysbiosis in children are an important section in pathogenesis of chronic constipation and possible heavy complications. The purpose of the research was to study the relationship between acid-base balance of blood and colonic dysbiosis in children with chronic constipation. Material and Methods. The analysis of 121 tests of the vein blood was performed in patients from 1 to 14 years old with various forms of chronic constipation. The researches were conducted with a gas-analyzer «ABL-700» Radiometer (Denmark) with the estimation of the following indices: blood pH, base actual abundance (BE), blood bicarbonate concentration (HCO3), lactate, anion difference, hematocrit and main electrolytes (sodium, potassium, chlorium), oxygen saturation, partial oxygen pressure, carbonic acid gas. For the estimation of colonic dysbiosis we carried out the bacteriological faeces research in the first day of patient`s admittance to hospital. The taken material of faeces in cultivation from 10-1 to 10-9 was sowed on the complex of the culture (Ploskireva, Endo, Levina, Blauroc, 1 central clinical hospital of the presidential administration of the russian federation, moscow, russian federation 2 stavropol state medical university, russian federation 1 ЦКБ с поликлиникой Управления делами президента Российской Федерации, москва, Российская Федерация 2 Ставропольский государственный медицинский университет, Российская Федерация Interconnection of correlations of the acid-base blood balance with dysbiosis in 121 children with chronic constipation was found in the study. Metabolic acidosis is revealed with a high lactate concentration, emaciation of the organism buffer systems on the lowering background of main blood electrolytes and dehydration. And in its turn it takes place on the marked translocation of the intestinal microflora. The lar...