Genera Paralepoderma, Leptophallus and Metaleptophallus have traditionally been classified as a group of closely related genera considered by most authors as members of the subfamily Leptophallinae, family Plagiorchiidae (Digenea, Plagiorchiata). At the same time the systematic position of the genus Macrodera was for a long time unstable and its phylogenetic affinities controversial. Different authors allocated this genus in the family Ochetosomatidae or as a type genus of separate family Macroderidae. The former three genera include parasites of snake digestive tract and the last one - parasites of snake lung. Some morphological features of adult and larval stages indicated, however, their possible close affinity. Molecular analysis based on the partial sequences of the 28S ribosomal DNA gene has demonstrated very close phylogenetic relationships between these four genera. The molecular data are supported by morphological characters of adult stages (first of all, presence of external seminal vesicles in all four genera), peculiarities of life cycle and chaetotaxy of cercariae. A hypothesis of the probable ways of speciation in this group is proposed.