The Chilean geological and climatic diversity allows the differentiation of a great variety of terrestrial and aquatic ecosystems Evidence provided by distributional patterns of freshwater species suggests a correspondence with Pleistocene glaciations, and some post-glacial tectonic events that affected the hydrography of the country The species of freshwater Chilean mollusks. unlike the marine species, have been undervalued Currently there are no biogeographic studies that would allow identifying distribution patterns and the possible processes that shaped them. A parsimony analysis of endemicity (PAE) and the richness of five hidrographic zones, based on 75 freshwater mollusk species, suggests the existence of three main biogeographic areas Northern (between latitudes 17 degrees-33 degrees S). Central-Southern (33 degrees-14 degrees S) and Southern (44 degrees-56 degrees S) Hydrographic zone V (44 degrees-56 degrees S), Included III the Southern area, has the highest endemism percentage (75 %), contrasting with hydrographic zone I (17 degrees-26 degrees S), included in the Central-Northern area, which registered the lowest value (42 %)