Parasitic infestations constitute an important part of aquatic animal diseases. In order to study the prevalence of parasitic skin infections of rainbow trouts in mordad of 1385, 5 breeding farms were selected and 386 rainbow trouts with the body weight of 250-300 gr were collected randomly from each farm and examined. Of the 1930 examined specimens of 5 farms in this study, 14 were infected by Ichthyophthirius sp. (0.7%), 890 by Trichodina sp. (46.1%), 41 by Dactylogyrus sp. (2.1%), 111 by Gyrodactylus sp. (508%) and 874 were without any parasitic infections (45.3%). The highest infection rate belonged to Trichodina sp.