RESUMEN
<p><b>OBJECTIVE</b>To determine the helminth parasites of Anas crecca (A. crecca) in one of proper refuges of Iran, Fereydunkenar.</p><p><b>METHODS</b>A total number of one hundred thirty-six gastrointestinal tracts of green-winged teal (A. crecca) were collected from Fereydunkenar, Mazandaran province during September and October 2011. The gastrointestinal tracts were examined for helminth infection.</p><p><b>RESULTS</b>The total infection rate was 70.50% (96) that 68.96% (40) of males and 71.79% (56) of females shown helminthes infection. The examined A. crecca harbored one species of Nematoda, Cestoda and two species of Digenea which were as following: Contracaecum larvae (from stomach wall), Diorchis stefanskii (D. stefanskii) (from small intestine), Hypoderaeum conoideum (from small intestine) and Notocotylus attenuatus (N. attenuatus) (from caecum), respectively. There was no significant difference in the prevalence of infection between examined males and females ducks in Hypoderaeum conoideum, D. stefanskii and N. attenuatus (P>0.05) whereas a significant relationship was observed between males and females in Contracaecum larvae (P<0.05).</p><p><b>CONCLUSIONS</b>Based on the results of the present study, we conclude that A. crecca plays a prominent role in transmission of mentioned parasites. In addition, this is the first report of Contracaecum larvae, D. stefanskii and N. attenuatus from A. crecca in Iran.</p>