Aim of the study:
The aim of the study was to demonstrate the medical properties of spring waters from Lesko based on their physicochemical analysis.

Material and methods:
There are three active sulphide springs and one mineral spring in Lesko. In water samples from Lesko (1, 2, 3) sulphides and hydrogen sulphide (divalent sulphur) were determined. The sulphide and hydrogen sulphide concentration in the springs was determined with iodometric, photometric and thiomercurimetric methods. All samples were checked for the presence of 7 heavy metals with the AAS method. In all examined waters, an additional quantitative analysis of such components as metaboric acid, orthosilicic acid, sulphur, bromine, iodine was carried out with two methods: the ICP-MS and the ICP-OES. Also, fluorine content was determined with ion chromatography.

Results and conclusions:
All waters from Lesko, except mineral water, contain sulphides. No heavy metals, including mercury and arsenic, were detected in all spring waters. No lithium or significant amount of iron and manganese were found. In the waters (1, 2, 3) no selenium and molybdenum were found. In the examined waters (1, 2, 3, 4), metaboric acid, orthosilicic acid, fluorine and iodides were found