The paper presents the results of hydrochemical research conducted on the Jasienianka flysch stream, a left bank tributary to the Biała Tarnowska river. The submontane catchment of the stream, with area of 94.40 m² is situated in the Malopolska province. The stream catchment area is covered mainly by agricultural lands (68.3%) and to a lesser degree by forests (25.5%), built-up and urbanized areas (6.2) located along the banks of the Jasienianka and its tributaries. The investigations were conducted in 2014. 21 selected physicochemical indices were determined in the stream water at five control-measurement points situated along the 13 km long stream reach. Along the analyzed stream section, only the water temperature, dissolved oxygen, BOD₅ and N-NH₄⁺ allowed to classify the waters to quality class I (maximum potential), whereas ChZT-Mn, EC, SO₄^2–, Cl^–, Ca²⁺, Mg²⁺, water pH and P-PO₄^3– did not fulfill the requirements for class II. The other indices, in compliance with the Minister of Environment Regulation of 2016, classified water to quality class II. Statistical analysis conducted using Kruskal-Wallis test revealed statistically significant differences in the indices values between the investigated measurement-control points for SO₄^2–, Mg²⁺, K⁺, N-NO₃^– and PO₄^3–. The assessment of water usable values revealed that it may be used for supply of water intended for human consumption only in the upper and middle reach. The Jasienianka did not meet the requirements for a natural habitat salmonid fish along its whole length because of high NO₂^– concentrations.