RESUMEN
Snail transmitted diseases are one of the major group of helminth parasitic diseases which have been established by trematode parasites. The larvae of trematodes [cercariae] use the snails as host. The purpose of the present study was to identify of cercariae released from Melanopsis spp. [M. doriae, M. costata, M. praemorsa, and M. nodosa] and evaluate their medical importance. Accordingly, 2, 266 Melanopsis spp. [fresh water snails] were collected from various agriculture canals in the central area of Khuzestan Province in the south west of Iran. 72 [3.1%] infected Melanopsis spp. snails were isolated and the cercariae were obtained by emerging or crushing methods. Subsequently, measurement and drawing were made on cercariae specimens and recognized. In some cases experimental infections were established in the animals for further iden-tification. A total of 4 cercarial families and 1 cercarial group were identified as follows: Heterophyidae: Haplorchis pumilio, H. taithui, Stellantchasmus falcatus and Centrocestus formosanus; Echinostomatidae: Echinochasmus milvi; Cyathocotyli-dae, Philophthalmidae and Monostome group cercariae [probably Notocotylidae]. These results have been recorded for the first time and these cercariae are of medical and veterinary importance