ABSTRACT: In the framework of regular hydrogeological survey, gauging of surface flow at 8 profiles and discharges from drainage adits at 2 stations with automatic recording were performed in the Neogene volcanics of the Štiavnické vrchy Mts. and Javorie Mts. from early May 2002 to late October 2003. Classic separation methods (Kille, Foster, Castany) were used to separate groundwater runoff from discharge time series. Also long-term observations of 4 profiles belonging to the basic network of the Slovak Hydrometeorological Institute were used for this purpose. For the period from V.2002 to X.2003, values of the average groundwater runoff were found in the range of 0.46 to 1.83 l·s-1·km-2, the median value was 1.22 and the average value 1.12 l·s-1·km-2. The minimum groundwater runoff was ranging from 0.11 to 1.53 l·s-1·km-2, while both average and median values were 0.57 l·s-1·km-2. Data for groundwater runoff determination for another 39 basins had been drawn on the basis of current meter measurements in four batches, performed in dry periods of 2003. However, despite the seemingly low-flow conditions, a noticeable impact of previous precipitation events to these values was found, as apparent and considerable volatility of specific runoff values in the individual watersheds and batches.