ABSTRACT: The Smilno tectonic window represents a shred tom off the Dukla unit and dragged into the Magura nappe. The hydrogeologicai structures, which are found in this area (Mikulášová, Dubová), are combined hydrogeologicai structures. The mineral waters issuing from these structures are of different chemical type (Mikulášová A1 40,6 mval% and S1/Cl 45,5 mval%, Dubová A1 60 mval% and S1Cl 33,4 mval%) and are bound to equal sediments of the Smilno tectonic window. This character of waters is the result of formation of mineral water in the environment of combined hydrogeological structure where the lower semi-closed hydrogeological structure in a certain ratio influences formation of mineral water in the upper open hydrogeologicai structure. So in the upper hydrogeologicai structure the resulting type of mineral water is forming. The lower hydrogeological structure is formed by sandstones of the Obidowa - Slopnice - Zboj unit, which were attested by borehole Zborov - 1.