In this study we analyze the composition of bat species of the Argentine Yungas, where 39 species have been recorded, number that indicates a high diversity of bats for the region compared with the total number of species in the country (66% of the species from Argentina). For comparative purposes we have incorporated in the analysis a revision of the species of the Bolivian Yungas. Since the mid-1970's, intensive field studies and surveys have been carried out in numerous localities of the Yungas in Argentina. The information obtained from personal collecting, plus the examination of museum specimens and literature records, allowed us to examine a total of 1682 specimens. One noctilionid, 12 phyllostomids, 13 vespertilionids, and 13 molossids were recorded in the area. For every species we include the specimens examined, additional records, distribution, reproduction and also provide additional comments related to the biology of the species observed by us during fieldwork studies. Biogeographical analyses were made considering the presence or absence of each species by degree of latitude along latitudinal gradients. The Yungas of Argentina was also compared with that of Bolivia and with other phytogeographic provinces, such as Chaco, Monte, Andean, and Paranaense regions, located at the same latitudinal range as the Yungas in Argentina.
