Different taxonomic problems of the Dactylogyridea Bychowsky, 1937 are discussed. From the recent point of view, all old genera need a careful revision. Taxa of higher ranks should be analysed taking into account their host phylogeny and zoogeography. The order Tetraonchidea Bychovsky should be disband and all its families should be moved to the Dactylogyridea. The aberrant families Montchadskyellidae and Anoplodiscidae also belong to the Dactylogyridea. Dactylogyrideans are most similar to the primitive monogeneans.