In the Biosphere Reserve of the Slovensky kras (Karst) mountain range, altogether 40 stoneflies (Plecoptera) species have been recorded as resident, their distribution depending on altitude, slope, water temperature, discharge, substratum, shade and regulation as well as organic pollution of the stream. Stenothermal cold water middle - mountain species of stoneflies penetrate into the north - eastern area, and mesothermal submountain ones into the south-western part. Based on discharge and water temperature 3 types of springs, occupied by characteristic stoneflies species can be distinguished. Saprobity and diversity indices have been recorded to depend on discharge and water temperature variability peculiar to the area.