ABSTRACT: Karst-fissure water, genetically related to the Mesozoic komplexes of carbonate minerals, is significant for the formation of drinking-water supplies in Slovakia. There were evaluated 13 significant drinking-water sources representing an important part of the water supply “Pohronský skupinový vodovod” in the mountain range "Veľká Fatra". As starting data were used chemical analyses of the process checking for the period from 1981 to 1994. Basic hydrogeochemical characteristic was showed that observed sources represented the typicaI carbonatogenic water. Evaluation of carbonate equilibrium confirmed the assumption supposing that in conditions of the karst-fissure and karst circulation the water is not saturated with carbonate. Based on obtained data investigated regime of groundwater quality was evaluated. Chemical composition of groundwater shows a typical changes in certain time of year, short-term, seasonal and long-term changes can be observed.