ABSTRACT: Drought occurrence in groundwater levels in Laborec catchment is evaluated in this paper by using the 90th percentile. This is tested and computed by the following three methods (1) the arithmetic average of the percentile obtained from the time series of individual hydrological years, (2) long-term values of the entire time series and (3) long-term monthly values of the entire time series of individual months. Indexes such as SWI in groundwater levels, SDI in discharges and SPI in precipitation amounts were tested by assessing the course of the average annual values of the evaluated parameters in that area. In view of the obtained results, drought in the evaluated hydrological parameter was assessed by calculating the ratio of the deficit and duration of dry periods in each year. Drought severity was calculated in this manner and then classified according to the established SDSI index.