en fish disease fish disease پژوهشي Orginal research papers The present study was carried out on digenean infection in two species of mugilid fish (<em>Chelon auratus</em> and <em>Chelon saliens</em>, Risso, 1810) in southern coast of Caspian Sea. One hundred and ninty eight fishes were totally studied. We identified the digenetic trematodes of three families, Haploporidae (adult Digenea), Heterophyidae (Metacercariae), and Diplostomidae (Metacercariae). Eyes, gills, stomach, intestine and pyloric caeca of fishes were infected with Diplostomidae (<em>Diplostomum spathaceum</em>), Heterophyidae (<em>Ascocotyle (Phagicola) longa </em>and <em>Ascocotyle </em>sp.), Haploporidae (<em>Saccocoelium obesum and S. tensum</em>), respectively. The results revealed that the stomach was the most infected organ (P=57%), and there was a significant difference between mean intensity of infection and sampling stations in Haploporidae (X²= 11.6, df= 3, p= 0.009) and Heterophyidae (X²= 10.2, df= 2, p=0.006). There was no significant difference between mean intensity of infection in three years and fish genders. <em>Ascocotyle (Phagicola) longa </em>and <em>Saccocoelium tensum</em> are reported for the first time in Iran. Another noticeable point is that the digenean parasites, which are prevalent in mullets, can cause disease in fishes. They are zoonotic (<em>Ascocotyle (Phagicola) longa</em>) and are important in point of view of ecology, economy and public health. Mullet, Metacercariae, Digenea, Zoonosis, Caspian Sea, Iran 1691 1703 http://jifro.ir/browse.php?a_code=A-10-3701-1&slc_lang=en&sid=1 M. Alizadeh Noudeh mabood.alizadeh@gmail.com 100319475328460042763 100319475328460042763 No Department of Biology, Aquatic and Marine Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran Department of Biology, Aquatic and Marine Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran J. Pazooki pazooki2001@yahoo.com 100319475328460042764 100319475328460042764 Yes Department of Biology, Aquatic and Marine Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran