Metabolic Syndrome (MS) is a widespread pathological condition, a group of interconnected metabolic disorders that contribute to the development of a number of severe noncommunicable pathologies. Natural mineral waters of various compositions are widely used in the correction of MS. Their biological activity and specificity of action is associated with the presence and number of specific components (micronutrients, biologically active substances). At the same time, the role of macrocomponents of the chemical composition of mineral waters with low mineralization in the implementation of their biological activity, most researchers do not pay enough attention.The purpose of the work: based on a comparative analysis of changes in the structure of internal organs of white rats with the model of MS, receiving mineral waters of the same balneological type (but quantitatively different macro composition), to assess the corrective effect of the macro component mineral waters for these changes.Materials and methods. The material of the study was the data of histological and histochemical studies of the internal organs of white rats of males weighing 280–320 g. Animals were ranked into 4 groups: I - group - intact rats that served as a control, ӀӀ group of rats with a model of MS; ӀӀӀ and ӀV groups, rats received the corresponding mineral waters against the background of MS modeling. The mineral waters used in the work were characterized by an increased (in close amounts) content of organic substances (C org.), similar in chemical but different in quantitative macro-component composition. At the same time, mineral waters practically did not differ in terms of total mineralization. Modeling of MS was carried out for 60 days by replacing 10% fructose solution in drinking water bowls, introducing white bread crackers into the diet, and excluding green mass from the diet. In groups where animals were corrected for MS, mineral waters were injected with an intragastric tube with olive at a dose of 1% of body weight daily, starting from the 60th day of the experiment, for 12 days. Upon completion of the experiment on day 72, histological sections (which were stained with hematoxylin-eosin) were made from the extracted pieces of the heart, stomach, liver and kidneys. The succinatedehydrogenase (SDH) and lactatedehydrogenase (LDH) activity were determined on the prepared cryostat sections.Using a light microscope, changes in the structure of the above organs and changes in the activity of oxidative-restorative enzymes were evaluated. When modeling MS in rats, an increase in the amount of visceral fat and a significant increase in fasting glucose levels were noted. In the studied internal organs there were signs of dystrophic changes, high activity of oxidative-restorative enzymes, signs of impaired water metabolism. In animals of the ӀӀӀ group, the use of mineral water was accompanied by normalization of the myocardial structure. In other organs studied, there were preserved foci of residual manifestations of dystrophy against the background of a general restoration of the structure.In animals of the ӀV group, upon completion of the mineral water intake, normalization of the structure of the stomach and myocardium and the preservation of diffuse manifestations of degeneration in the liver and kidneys were established. The activity of oxidative-restorative enzymes was approaching normal; some manifestations of changes in water metabolism in the animal organism persisted. At the end of the use of both mineral waters, a significant decrease was found in the content of visceral fat around the intestines, renal capsule, under the pericardium, which correlated with a decrease in the animal’s body weight and restoration of the fasting blood glucose level to the cereal level. The authors believe that the established features of the corrective effect of both mineral waters on changes in the structure of internal organs are explained not so much by the difference in the content and ratio of the bioactive component (C org.), But by differences in the content of macronutrients.In mineral waters obtained by rats of group III, the content of Cl– and SO4+2 ions is 2.30 and 3.67 times, and Ca2+ and Мg2+ ions are 2.75 and 4.57 more than in mineral waters, which received rats of group IV. However, the content of HCO3–, Na+, K+ is 1.14 and 1.30 times higher in the mineral waters obtained by rats of group IV. Conclusions. It can be assumed that the minerals involved in the implementation of the biological activity of mineral water, changing the metabolic background, on which the bioactive element of mineral water in the form of C org., Has a more intense corrective effect.