Triatoma platensis, an ornitophilic species, found in Argentina, Bolivia, Paraguay and Uruguay is reported for the first time in Brazil. It was found in the county of Uruguaiana (Rio Grande do Sul) in nests of Anumbius annumbi (Vieillot, 1817) (Passeriformes, Furnariidae) where it cohabited with cricetids belonging to the species Orizomys flavescens. None of the seven individuals collected were infected by Trypanosoma cruzi.