ABSTRACT: The contribution presents an evaluation of the exploitable groundwater resources and reserves in the Slovak Republic, and shows application of the evaluation in the Balance of National Water Management of Groundwater and hydroecological plans executed by the Department of Groundwater Quality and Quantity (KKPzV) at The Slovak Hydrometeorological Institute (SHMU). The article also documents development and the ways of evaluation of exploitable groundwater amounts, water withdrawals, groundwater balances and ecological plans from past to present. The current data about exploitable groundwater amounts and water supplies are stated.