Brazil is a megadiverse country with more than 180 bat species. However, bat conservation in Brazil is limited by knowledge gaps concerning the ecology and distribution of many species. This is especially severe for aerial insectivores, comprising eight of the nine families present in the country. Reliable data on echolocation calls is thus key to gather information on the occurrence, activity patterns, habitat preferences and, consequently, on the conservation status of those species. We integrated information on echolocation calls of aerial insectivores occurring in Brazil from the literature and our own data. Then we identified regional changes in species acoustic profiles, uncovered gaps of knowledge, both in terms of species and regions sampled, and pointed out which species are acoustically recognisable in a reliable way. From the 93 aerial insectivores we considered to occur in Brazil, 65 have been acoustically described. However, for at least 26 species there is no information on their echolocation calls, nor sound files available to allow their identification. We found regional acoustic variability in at least 10 bat species, which may reflect previous changes in other aspects of the phenotype and local adaptations, making them priority candidates for investigating the actual magnitude of such variation, morphological variations among populations, or the existence of cryptic species complexes. We believe large-scale and long-term acoustic monitoring is fundamental to elucidate how Brazilian bats respond to the severe human-induced landscape modifications in this megadiverse country and their possible associations with climatic changes.