The aim of this study is to characterise, quantify and map the genetic diversity within and between local populations of Leptaxinae (endemic and threathened landsnails on the Azores archipelago) with identification of 'Evolutionarily Significant Units' for conservation.This comprises a population genetic study based on protein electrophoresis ('Polyacrylamide Gel Electrophoresis' and 'Isoelectric Focusing') and 'Random Amplified Polymorphic DNA', a morphologic (a.o. 'Scanning Electron Microscopy') and morphometric investigation of characters from the shell and the genital tract and a phylogenetic analysis based on sequences of nuclear and mitochondrial DNA.