There is hardly any agreement about relationships among the families of the Limacoidea sensu lato (Gastropoda: Stylommatophora) in modern classifications. The delimitation of this group and its systematic position within the Sigmurethra are discussed. A cladistic analysis of the familes of the Limacoidea sensu lato is given, based on a detailed consideration of all relevant characters of the genitalia, nervous system, muscle system, lung, digestive system, external morphology and shell. The Sagdidae and the Helicoidea are included in the cladistic analysis as outgrous. The Helicoidea (including Arionoidea, Polygyridae, Camaenidae) proved to be the sister-group of the Limacoidea sensu lato. According to the strict consensus tree of 27 most parsimonious cladograms, the main groups of the Limacoidea sensu lato are shown to be related as follows: ((Staffordiidae, ((Dyakiidae, Gastrodontoidea) (Parmacelloidea, ((Zonitoidea, Helicarionoidea), Limacoidea)))). The reliability of the individual clades and the subdivision of several familes are discussed.