Physical, chemical and spatial variables of bat guano deposits (pH, percentage of organic matter, distance from the cave entrance, area and shape of the deposits) were analyzed with regard to the richness and abundance of arthropod communities in Morrinho Cave, Bahia State, Brazil. In total, 12,356 individuals were sampled, belonging to 85 morphospecies in at least 26 families of Acarina, Araneida, Pseudoscorpionida, Isopoda, Coleoptera, Collembola, Diptera, Ensifera, Heteroptera, Homoptera, Hymenoptera, Isoptera, Lepidoptera, Neuroptera, Psocoptera, Siphonaptera, Thysanoptera, and Zygentoma. Richness and diversity of invertebrates were correlated with the area and distance from the cave entrance, pH, organic content and moisture content of the guano piles. Communities associated with bat guano are apparently more dependent on the guano microenvironment itself than on the overall cave environment.