Water has been tested from 10 test points located in the northern parts of Sanok and Lesko districts. The following analytical methods have been used: AAS (FAAS, CVAAS, HGAAS), ICP-MS, ICP-OES, Ion chromatography, Acid-base titration, Argentometry, Turbidimetry and bacteriological examinations. One has recognized two “natural mineral hard medium-mineralized waters” with low iron content. Four sulphide springs have been found of which Lesko spring has water which can be characterized as “a specifictherapeutic sulphide water” containing divalent sulphur assayed by iodometry above 1 mg · dm–3, without any bacteriological reservations. Water from Lesko, apart form small amounts of metaboric and orthosilicic acid, is slightly alkaline with a strong negative ORP potential (–230 mV) making it pro-health (an antioxidant that eliminates free radicals). In all waters the presence of heavy metals, arsenic, lithium, iron, manganese, alkali metals and alkaline earth metals has been tested. The influence on the human body of analytically marked substances has been described.