ABSTRACT: Regional hydrogeological investigations, explorations and surveys represent a primary background information on hydrogeological settings of the Slovak territory. Based on these it is possible to decide correctly on water management measures and landuse planning decisions, taking into account distribution and movement of groundwater, to project detailed hydrogeological explorations, to extract input data on boundary conditions and aquifer hydraulic properties in regional groundwater flow modelling studies, and to evaluate the degree of groundwater sources pollution and the risk of contamination of another groundwater sources. Today, resp. in the time period between the present time and the milestone represented by the year 2000, we can recognise several types of hydrogeological labours with regional character, which were undertaken on the territory of Slovak Republic: (a) hydrogeological surveys connected with estimation of groundwater resources; (b) construction of basic hydrogeological and hydrogeochemical maps, mostly in the scale of 1 : 50 000; (c) construction of purpose hydrogeological maps and maps of natural water quality in the framework of edition of maps of geological factors of environment, also mostly in the scale of 1 : 50 000; (d) regional hydrogeothermal evaluations of prospective geothermal areas / areas of geothermal waters; (e) hydrogeological explorations connected with delineation of protection zones, mostly for the sources of natural healing waters and sources of table drinking mineral waters.