ABSTRACT: The hydrogeological and hydrogeochemical properties of groundwater in the Žiar Mts. and adjacent area are presented in the paper. The results were mostly obtained from the project “Basic hydrogeological maps of selected regions of Slovakia” held by the State Geological Institute of Dionýz Štúr. Additional data from field mapping of 1,215 springs documented during 2002-2004 over a total mapped area of 185km2 are supplemented with new measurements in 2010-2012. Crystalline rocks and Mesozoic carbonates dominate this area of hydrogeological significance; with especially limestones and dolomites. Excellent hydrogeological properties were apparent in Neogene volcanic rocks, where natural springs with yields up to 5 L·s-1 were documented. One exception was the yield of up to 40.56 L·s-1 recorded for groundwater drained by a tunnel. Most high yield springs here are used for water supply. and the groundwater chemical composition correlates strongly with the mineral character of host rock formations. Genesis of the groundwater varies because of this area’s complex geological structure; with several groundwater chemical types typical for the area. Ca-HCO3 and Ca-Mg-HCO3 water types dominate the natural uncontaminated groundwater of the first aquifer.