Due to an inadequate knowledge about threats to the sea turtle, we aimed to evaluate the helminth fauna of Chelonia mydas which had died on the southern coast of Espirito Santo, Brasil and described the associated tissue pathological lesions. Retrospective and prospective studies on turtle parasites were conducted and tissues samples were collected. 106 of 212 of sea turtles (50 %) were parasitized, and 47 of 106 of infected animals 43.0 % (47/106) were in poor health condition. Seven trematoda families covering 19 different helminths species were identified. Turtles were inhabited with one or more species of parasites, and there was no significant association between parasitism and weakness of the animals. Trematode eggs, with or without giant cells in tissues of various organs were observed.