The main objective of this graduation thesis was to create a Collection of freshwater snails, make a taxonomic analysis of species and display distribution of families of freshwater snails in the Croatian territory. Freshwater snails from samples collected during several years of malacological research, are determined by the level of species or subspecies. Than there was recorded a total number of individuals of each species, the number of adult and juvenile snails and the number of empty shells. The snails were kept in plastic containers which contain 96 % ethanol. Samples have inventory number, localities are georeferenced and using Microsoft Excel 2010, the database was created. The collection contains 280 samples in which there are 43 species from 12 families of freshwater snails. Three types are determined by the level of subspecies. According to the IUCN categories of threat, there are two types of near threatened (NT), two vulnerable (VU), two deficient (DD), and 36 species of least concern (LC). The Collection has 17 endemic species of Europe, and Graziana papukensis, G. slavonica, Sadleriana supercarinata and Radomaniola curta germari are endemic species of Croatia. Four species are strictly protected, and Anisus vorticulus is part of NATURA 2000 in Croatia. None of the species listed in the Collection is not invasive, and non-native are Physella acuta and Ferrissia wautierii. The family with the largest number of species, 11 of them, is the family Hydrobiidae, and Planorbidae family has 10 species. The highest areal distribution has family Planorbidae which was found in 49 watercourses, while the family Pyrguliidae has the smallest range and is represented only in the Cetina River. Families Emmericidae and Pyrgulidae are only present in rivers of the Adriatic watercourse, while the other ten families were represented in the rivers of the Adriatic and the Black Sea watercourse. The results of this graduation thesis will serve as a basis for future research into the extent and vulnerability of freshwater snails in Croatia, and the collection will be supplemented in the future with new samples.