Result obtained during ten years research work (1990-2000) on distribution of monogenean fauna Iranian fishes indicates that its composition of monogenean fauna of Iranian fishes depends on their habit and since Iran includes three different zoogeographical zones with highly endemic fish hosts, its monogenean parasites have specific composition. The Caspian fauna is characterized by relatively great diversity of monogenean species (eleven genera and at least forty-eight species). Presence of some species with sphymoid type of anchors is one of its speciation. The Iranian part of Mezopotomian (Tigris) fauna (six genera and at least twenty-six species) is characterized by distinct monogenean parasites, for instance, presence of Dogielius type of anchors and prevalence of Dactylogyrus spp. with morphilogical peculiarities not similar to Sarmatian fauna. The most of its specific character is the shape of dorsal and ventral bar in Dactylogyrus species found in the Tigris Zone. Endemism in the a forsaid zone is high therefore species of Dactylogyrus will be increased more. The oriental monogenean fauna of Iran (three genera and at least eleven species) shows special characteristics, amongthem, the presence of one connective dorsal bar only, presence of varicorhinoid type of bar and haptor would suggest that aforesaid zone of Iran has been influenced by the Indian fauna
