The only published report of bats from the Antillean island of Saint Barthelemy (French West Indies) was by Allen (1911) based on three specimens of Tadarida brasiliensis in the collections of the Museum of Comparative Zoology at Harvard University (MCZ). Believing that this paucity of records was an artifact of collecting effort rather than a biological phenomenon, we visited the island during 19–25 May 2004. Our work resulted in the collection of four species of bats not previously recorded from the island, as well as additional specimens of T. brasiliensis. Subsequent to our field studies, we examined Allen’s (1911) original material, as well as several specimens previously obtained on Saint Barthelemy in 1982 that were deposited in the National Museum of Natural History (NMNH) but had not been recorded in the literature. Saint Barthelemy (188N, 638W) is located 30 km south of Saint Martin and was connected to that island and Anguilla during the Pleistocene (Pregill and Olson 1981). The island has an arid climate, and steep mountains (highest point 281 m) constitute much of its 25-km2 area. Saint Barthelemy receives approximately 1000 mm of rain annually and has mean temperatures of 218C and 25.58C in winter and summer, respectively. We found significant tourism development and a paucity of fresh water on the island. Agriculture and tourism development have done little to alter the native flora, which comprises aridand saline-adapted plants such as lignum vitae (Guaiacum officinale), manchineel (Hyppomane mancinella), geranium tree (Cordia sebestena), sea grapes (Coccoloba uvifera), and Englishman’s head cactus (Melocactus intortus), none of which are particularly beneficial for bats. The flora on St. Barthelemy that is potentially useful as food or shelter for bats include trees such as flamboyant (Delonix regia), frangipani (Plumeria spp.), sabal palm (Sabal palmetto), and royal palm (Roystonea spp.), as well as scattered banana (Musa spp.), mango (Mangifera spp.), and breadfruit (Artocarpus spp.) trees. Because much of the island is composed of limestone, the discovery of numerous cave systems that provide shelter for at least four of the five species of bats now known from the island is not very surprising. Mist-netting for bats was conducted in a variety of habitats that exhibited some fruiting trees. Bats were measured and examined at the end of the evening: weight (g), length of forearm (mm), reproductive status (testis length wmmx, crown-rump length of embryos wmmx, and lactation), and tooth wear. Length of forearm and cranial measurements (mm) were taken from museum specimens using digital calipers. Voucher specimens from our work were deposited in the research collections at the Museum at Texas Tech University (TTU) and the Laboratoire de Zoologie Mammiferes and Oiseaux at the Museum National d’Histoire Naturelle in Paris (MNHN).