Aim of study: To establish quantitative relationships linking composition and properties of human venous blood with a water-salt composition of the Eurasian hydro-mineral resources (mineral waters and therapeutic mud) Materials and Methods: To identify the composition and properties of human venous blood and of natural mineral waters and therapeutic mud we introduced the concept of "characteristic indicator" of water-salt solutions, Ф, connecting a total mineralization, ion composition and physiological parameters of human blood. Mathematical model, allowing to perform the comparative assessment of the effects of hydro-mineral resources on the physiological state of the human body, was implemented as a universal computer program for calculation of analytical dependencies of the characteristic indicator composition of blood φ, as a function:  i i B  , where: φi - characteristic indicator of blood calculated at i-th blood biochemistry index; Bi - laboratory biochemical indicator of a certain i-th sample of blood; α and δ - constants. Results: 1. Characteristic indicators of composition and properties of hydromineral resources (Ф) and venous human blood (φ) allow a high degree of accuracy to assess the effectiveness of the impact of mineral water and mud on the human body according to the biochemical blood test; 2. Characteristic indicators allow the assessment of the physiological condition of the body and can be used for the organization of national and European monitoring systems of social health; 3. Analytical dependence function ln ( ) 7,0462 ln( ) 627,22 2 2  pO pCO Hb allow a quantitative assessment of laboratory data on the content of hemoglobin, carbon dioxide and oxygen in the blood before taking treatments. Conclusions: According to the results of chemical studies can draw the following conclusions: 1. The chemical composition of a patient's blood prior to the adoption of procedures of mud treatment is identical to the composition of mineral waters. 2. Influence of therapeutic impact of the hydromineral resources on the person is accompanied by a decrease in the content of ions  3 HCO and increased content ion Cl . 3. The change in the ionic composition of venous blood as a result of balneological procedures increases the solubility of oxygen, increase of hemoglobin and decrease of glucose.