A total of 281 guano samples were collected from caves (N = 181) in 8 European countries (Bulgaria, Czech Republic, France, Hungary, Italy, Romania, Slovakia and Slovenia) and attics in the Czech R. (N = 100). The correlation of detection of mycobacteria between Ziehl-Neelsen (ZN) microscopy and culture examination and qPCR was strong. ZN microscopy was positive in guano from caves (58.6%) more than double than positivity in guano from attics (21.0%; P <0.01). From 89 mycobacterial isolates (73 isolates from cave guano and 16 isolates from attics’ guano) 68 (76.4%) isolates of 19 sp., ssp. and complex were identified as members of 3 Groups (M. fortuitum, M. chelonae, and M. mucogenicum), and 4 Complexes (M. avium, M. terrae, M. vaccae, and M. smegmatis). A total of 20 isolates (22,5%) belonged to risk group 1 (environmental saprophytes), 48 isolates (53.9%) belonged to risk group 2 (potential pathogens), and none of isolates belonged to risk group 3 (obligatory pathogens). When comparing bat guano collected from caves and attics, differences (P<0.01; Mann-Whitney test) were observed for the electrical conductivity, total carbon, total organic and total inorganic carbon. None difference (P> 0.05; Mann-Whitney test) was found for pH and oxidation-reduction potential parameters.