From October 2006 to March 2008, sixty specimens of Paralichthys isosceles, were captured in the littoral of the State of Rio de Janeiro Brazil. The present study deals with the taxonomic identification of the cestodes parasitizing this fish species, as well with the analysis of parasitological indexes, sites of infection, taking into account the hygienic-sanitary importance of the host in Brazilian and foreign markets. Fifty-six (93.3%) out of the collected fishes were infected with at least one specimen of metacestodes. Diphyllobothriidea were represented by plerocercoids of two species: Diphyllobothrium sp. 1 (similar to D. latum) in stomach, stomach mucosa and mesentery and Diphyllobothrium sp. 2 (similar to D. dendriticum) in intestine, liver, ovary and abdominal cavity. Trypanorhyncha, were represented by Grillotia carvajalregorum, in stomach, intestine, liver, mesentery, abdominal...