A study of fluid inclusions from the ore samples from the Mlynna dolina valley (Nizke Tatry Mts, Western Carpathians) has provided information on the formation conditions of the mineralization. Arsenopyrite and pyrite are accompanied by quartz with CO₂-rich, low-to-moderately saline (3.6–15.4 wt. % NaCl eq.) fluid inclusions with homogenization temperatures of 281–365 °C and estimated trapping pressures between 150 and 350 MPa. Arsenopyrite thermometry suggests a crystallization temperature of 320–380 °C, thus overlapping the fluid inclusion data. Subsequent decrease in temperature and pressure were probably responsible for the fluid devolatilization and the precipitation of stibnite and berthierite at temperatures of 200–250 °C and pressure <100 MPa. Formation conditions of chalcopyrite – tetrahedrite assemblage are poorly constrained due to the paucity of fluid inclusions. These homogenize at 157–187 °C and indicate an aqueous fluid with a salinity of 17.9–22.0 wt. % NaCl eq. Superimposed galena-sphalerite assemblage is hosted by quartz containing fluid inclusions with a salinity of 16.3–22.5 wt. % CaCl₂ eq. and homogenization temperatures between 95–202 °C. Preliminary thermometry and mineralogical data for mineralizations of the Mlynna dolina valley suggest a close genetic similarity to other ore deposits in the Nizke Tatry Mts.