Bat guano supports an assemblage of organisms that varies depending on the species of bat producing it. To determine whether these differences in community structure may be due to differences in guano composition, we analyzed guano from frugivorous (Pteropus rodricensis), sanguivorous (Desmodus rotundus), and insectivorous (Tadarida brasiliensis) bats. We found no differences among species in organic matter or lipid of guano. Desmodus guano contained more carbon (C) than Pteropus guano. The latter contained less nitrogen (N), and the former contained less phosphorous (P) than guano of the other two species. Pteropus guano had a higher C:N ratio, and Desmodus guano had higher N:P and C:P ratios than the other two species. These differences in guano composition suggest that guano from bats in different feeding guilds may affect ecosystem structure and dynamics differently.