The cave fauna of the karst complex of Frasassi (Genga. Ancona, Italy), which includes a tourist attraction, was surveyed to provide detailed information on the hypogean animal populations. Indeed, for this area, only sporadic and limited studies are known in the literature to date. The bat populations, recently analyzed by Bassi and Fabbri (1986-87), were excluded from our study. Ten collection campaigns were carried out in 12 different caves, including the tourist site, over a span of two years. Three caves were considered in all the collections and the others only on one or two occasions. The animals were captured for the most part on sight. Faunistic analysis was supported by specialists in systematics for some animal groups. A total of 57 taxa were identified. Two endemisms were confirmed: the amphipod crustacean Niphargus ictus and the carabid beetle Duvalius bensai Iombardii. Noteworthy are the histerid beetle Gnathoncus Cerberus, to date only known in Sardinia, and a pseudoscorpion belonging to the genus Roncus, probably a new species, currently under study by a specialist. A karyological study on the plethodontid salamander Speleomantes italicus revealed the close similarity of the Frasassi population with others of the Italian peninsula. Overall, the animal community appears relatively homogeneous, indicative of a very stable cave community throughout the entire karst complex of Frasassi. Only the show cave has an almost complete lack of animals, due to low organic supply. This homogeneity can be explained by the close geographical location and common origin of the caves. Moreover, the caves develop predominantly horizontally, located at 200 to 490 m a.s.l. Our data are in agreement with the few available reports on other caves in central Italy. According to our study, the low level of adaptation to cave dwelling was indicated by the 50% troglophile species, whereas only two species were troglobite. The large number of the first and the low number of the second types are related to the geological age of the complex and they are the consequence of a relatively recent faunistic colonization.