Abstract. The thermal ground waters used for spa complexes in Zilinsky and Banskobystricky regions in the Slovak Republic and in Beregovo, Transcarpathian region, Western Ukraine, were analyzed for gammaradiation level, content of selected radioactive elements and physico-chemical characteristics. Comparative analysis of the thermal ground waters showed that waters in Beregovo had the highest radiation level in terms of gamma spectrum, which was about two times higher than the limit; in contrast, radiation levels of research sites in the Slovak Republic were within Slovakian standard limits. The concentrations of radioactive elements Ra 226 and U in the thermal ground waters in Beregovo, Ukraine and in Turčianske Teplice, the Slovak Republic were within the limit.Researched thermal ground waters in the Slovak Republic and Ukraine had similarities in geomorphological characteristics and tectonic background. However, physico-chemical characteristics of waters were diverse: while SO 4 2-and HPO 4 2-concentrations were close for all research tests, waters in Beregovo showed highest levels of concentrations of Ca 2+ , Na + , Fe 2+ , NH 4 + , and Cl -ions concentrations. Recommendations on improvement of the environmental situation at the research sites and further use with respect to sustainability were developed.