A total of 555 bats representing nine species were captured in Arizona and cultured for Histoplasma capsulation. Fifteen bats from five sites in southern Arizona yielded the fungus. Eight of these bats were Tadarida brasiliensis mexicana (Mexican free-tailed bat) and seven were Leptonycteris sanborni (long nosed bat). The latter, a nectar-feeding species, is reported for the first time as harboring this organism. The ecology of the positive sites and the possible role of bats in the epidemiology of histoplasmosis are discussed.