The chiropteran collection that has been recovered from the two chronologically different fossiliferous assemblages of the Loutra Almopias Cave A (Pella, Macedonia, Greece) is studied. The specimens retrieved from the cave's floor sediments (LAC) are of the Late Pleistocene, whereas the specimens retrieved from the elevated chamber LAC Ia are of latest Pleistocene age. The first comprehensive systematic taxonomy and biogeographic analysis of a fossil chiropteran fauna from the Greek region was accomplished, based on the determination of the 9,004 chiropteran specimens. This resulted in the identification of 17 species from LAC and 20 from LAC Ia from three families (Rhinolophidae, Vespertilionidae, Miniopteridae) and nine genera (Rhinolophus, Myotis, Nyctalus, Pipistrellus, Vespertilio, Eptesicus, Plecotus, Barbastella, Miniopterus). Seven bat species described from the Loutra Almopias Cave A are the first known records in Greece and one species is the first Late Pleistocene record from the Balkan Peninsula. Eighteen species refer to the southernmost appearance of the Late Pleistocene of the Balkan Peninsula. Loutra Almopias Cave A served primarily as a nursery roost for many bats, and secondarily as a warm refuge during colder periods. Almost all of the chiropteran species described in this paper are now permanently resident in the region adjacent to the cave. Almost all bat species found in the Loutra Almopias Cave A are also present in the records of several localities from the Balkan Peninsula as Similarity analysis between the chiropteran faunas is indicative of an equivalent distribution in the region during the Late Pleistocene. In conclusion, the Late Pleistocene bat fauna from the Loutra Almopias Cave A is, up to date, the richest and most diverse not only from the Greek region, but also from the Balkan Peninsula.