Abstract Abstract: Trichiurus lepturus (Actinopterygii, Perciformes) is a commercially and economically important fish. A total of 60 specimens of this cutlassfish were collected of the coast the municipalities of Niterói and Cabo Frio, state of Rio de Janeiro, Brazil. The fish were measured, necropsied, filleted and had their organs investigated for digenetic trematodes. Taxonomic identification was based on morphological and morphometric characters. The specimens of T. lepturus were parasitized with adult specimens of Lecithochirium monticellii. Parasite indices of prevalence, intensity, mean intensity, abundance, mean abundance, range of infection, and site of infection of parasitic species were evaluated. Notes on the taxonomy of the parasite were also included. This is the first report of L. monticellii parasitizing T. lepturus in Brazil.