Chitinase was found in the intestines of 9 species of 6 genera of bats of Indiana. Included were the northern myotis, Myotis septentrionalis; the little brown myotis, M. lucifugus; the Indiana myotis, Myotis sodalis, the big brown bat, Eptesicus fuscus, the eastern pipistrelle, Pipistrellus subflavus, the evening bat, Nycticeius humeralis, the red bat, Lasiurus borealis, the hoary bat, L. cinereus, and the silver-haired bat, Lasionycteris noctivagans. Chitinase was found in summer and in winter, but at significantly lower levels in winter. Chitinase in summer may help to separate parts of insects by breaking down softer connective tissue. In winter, it may break down remnants of chitin left over from summer foraging and could even serve as a supplemental source of energy and nutrients. Chitinase was produced in these bats by 6 previously known species of chitinase-producing bacteria, 2 of Serratia, 3 of Bacillus, and 1 of Enterobacter, and by 4 species previously unknown to produce chitinase, Hafnia alvei, Citrobacter amelonaticus, Enterobacter aerogenes, and E. cloacae.