Аннотация:The Essentuki mineral groundwater (EMGW) basin involves the unique wide variety of mineral waters having different TDS, pH,chemical, and gas composition. TDS changes from fresh (0.5-0.9 g/l) to high-salinity (10-13 g/l) and strongly depends on thechemical composition of water. The region is characterized by a widespread of high pCO2 sparkling Ca-Na-HCO3-Cl waters, whichare a trademark as «Essentuki 4» and «Essentuki 17», and has strong therapeutic properties. Geothermal conditions, major andmicroelements, isotopic characteristics of water (δ18О and δ2Н), and gas (δ13С in CO2 and СН4,3Не/4Не) phases of carbon dioxidemineral waters of EMGW basin are considered.