Land gastropod fauna of the valley of Pieniński Potok, tributary to the Dunajec River, was studied qualitatively and quantitatively in 1995–1998. Among plant communities Carpathian beech forest dominates. Forty nine species (42 in quantitative samples) of 16 families were recorded, Clausiliidae, Zonitidae and Helicidae being the most numerously represented. The density ranged from 106 to 253 individuals per m², the dominants being Vestia gulo (Bielz), Macrogastra ventricosa (Drap.), subdominants Balea biplicata (Mont.) and Vitrea diaphana (Studer); dominants among litter species being Vitrea diaphana, Aegopinella pura (Alder) and Carychium tridentatum (Risso). These species are the most typical and indicative of the malacocenosis of the Carpathian beech forest. The malacocenosis is multicomponent, polymictic (TDI = 0.93). Simpson's diversity index is high (I = 0.065).