ABSTRACT: Value of the groundwater runoff is very important input value in the process of groundwater usable amounts estimation. Groundwater runoff value changes with the change of basic climatic parameters affecting the hydrological balance in the area. Accepting documented climate changes in the Slovak territory, it is necessary to re-evaluate changes and time development of groundwater runoff values. Different methods were used for groundwater runoff estimation in two catchments in the Eastern Slovakia – Topla at Bardejov and Sibska voda at Klusov-Klusovska Zabava. The results showed lower specific groundwater runoff values estimated for Sibska voda stream, reaching only 49 – 89 % of those estimated for Topla River. Besides of groundwater runoff value estimation, prediction for its time development was made using climatic scenarios CCCM 1997 and CCCM 2000. In the worst prediction case fulfillment the groundwater runoff could decrease on Topla River on 12 % of the today state in 2081 – 2090 period.