Phylogenetic relationships among 20 Central European populations of the genus Bythinella have been reconstructed on the basis of morphological characters and allozymic variation presented in our previous papers. Fitch-Margoliash additive trees based on Euclidean distances were constructed for morphological data, and genetic distances (Prevosti, unbiased Nei, Cavalli-Sforza and Edwards arc distances) were computed. Of all the genetic trees which were fairly similar, those based on Cavalli-Sforza and Edwards arc distances seem to reflect the phylogeny best. 21 discrete morphological character states were used to reconstruct phylogenies by means of the parsimony method. Allele frequencies were used directly to compute a tree of interpopulation relationships by means of the frequency-parsimony method. The inferred morphological and allozymic phylogenies differ in their topology and the amount of evolution (measured as the number of changes averaged over all reconstructions) along the corresponding branches; the correlation between them is statistically insignificant. The species rank of most of the postulated morphospecies seems doubtful and requires a further study.