An updated list of 653 species is reported for Iguazú National Park and surroundings based on 12 years of study, bibliographic information and data from several public and private entomological collections. This is the first published list of butterflies from an area known for its richness and abundance of species, particularly the Iguazú Falls area, for which, surprisingly, there only exist partial lists or isolated citations of species in scattered publications. Six new species for the Argentinean fauna are reported. The diversity of the area is compared to that of other protected areas in Misiones and southern Brazil. The area is important as a refuge of many species only present in this area of the country, despite suffering increasing threat from urbanization and fragmentation of the remaining forest areas close to the park.
