This paper presents a total of 11 known CRUSTACEAN parasite species from 51 host species belonging to 7 families, with 17 genera reported from cultured and wild fishes in three faunal regions of Iran. Among them, one belonging to Branchiura order, namely Argulus foliaceus, was found on Capoeta capoeta in Makoo Reservoir as well as on Cyprinus carpio, Chalcalburnus sp., Hypophthalmichthys molitrix and Mastacembelus mastacembelus in Zarivar Lake. The other 10 species belonging to Copepoda order include 1) Ergasilus sieboldi, found on the gills of 2) Barbus sharpeyi, B. luteus, Aspius vorax and Cyprinus carpio; 3) E. peregrinus on Ctenopharyngodon idella and Leuciscus cephalus in Khandaqloo Reservoir; 4) Lamproglena compacta and 5) L. polchella on the gills of infected fish species inhabiting Tigris, Caspian and Oriental Regions of Iran. 6) Tracheliastes longicollis on the fins of Capoeta capoeta and Leuciscus cephalus; 7) T. polycolpus on the fins of Capoeta trutta, C. capoeta and Leuciscus cephalus in water bodies situated in Azerbaijan Province (Caspian Region) and Kurdistan Province (Tigris Region), 8) Achtheres percarum on the skin and fins of Sander lucioperca and Perca fluviatilis in Anzali Lagoon and Sefid-rud River in North of Iran (Caspian Region); 9) Pseudotracheliastes stellatus on the skin of acipenserids in Caspian Sea and finally 10) the most economically significant parasite, Lernaea cyprinacea, which is commonly found on cultured cyprinids in ponds and natural water bodies. Furthermore, several unknown CRUSTACEAN species belong to both orders identified to genus level, which need further study for a detailed description. Geographical distribution as well as host ranges of the mentioned parasites are presented and discussed.