(Uploaded by Plazi for the Bat Literature Project) The Yungas of central Peru constitutes an ecosystem with an interesting diversity of wildlife species, among which the communities of phyllostomid bats are not yet well known. Phyllostomid bats are considered a good bioindicator, due to their abundance and taxonomic stability. In this study, we provide a better understanding of patterns of phyllostomid assemblages at two elevations and during two seasons in the Central Peruvian Yungas. We sampled phyllostomid bats with ground-level mistnets at one site in the montane forest (the higher elevation) and at one site in the premontane forest (the lower elevation) in Chanchamayo, Junín, during the dry and wet seasons. We captured 297 individuals belonging to 31phyllostomid species and ve guilds. Species richness was higher overall at the premontane site. The species richness and relative abundance at the premontane site were higher in the dry season, while the montane site did not show seasonal di erences. Phyllostomid assemblages at the two sites shared four species, while 20 species were captured only at the premontane site, and seven only at the montane site. Further studies are needed to obtain a better understanding of the entire bat community and species with altitudinal movements. We recommend a special focus on aerial insectivores. Our study contributes to a better understanding of phyllostomid bat assemblages and their distribution in the Central Peruvian Yungas. We hope this information will become an important piece of biodiversity information for the region that will lead to improved decision-making. The richness and relative abundance of the bat species recorded in this study as well as the presence of Vampyressa melissa and Gardnerycteris koepckeae, which are categorized by the Peruvian Government as Vulnerable and Critically Endangered, respectively, demonstrate the need for conservation e orts to protect the forest of Chanchamayo, Junín, especially in the montane areas. In addition, the information generated by this study can serve as a baseline for future comparisons to examine possible e ects of climate change on species distributions that may force some species to move to higher elevations.