Otoliths collected from the Late Oligocene of the Eger area revealed the presence of 52 teleost taxa from subtropical to warm temperate waters. Two successive faunas, which have only three species in common, are identified: the Kiscell Clay fauna, comprising 30 taxa, and the Eger Formation fauna, comprising 25 taxa. Although both belong to distinct stratigraphic horizons, the differences are entirely due to ecological factors. The Kiscell Clay provided an association of deepwater fishes, quantitatively very rich in otoliths of mesopelagic fishes, while the Eger association reflects a continental shelf fauna, in which three distinct assemblages corresponding to the progressive shallowing of the environment can be distinguished. The Late Oligocene teleost fauna from the Eger area shows a striking resemblance with the one from the Late Oligocene (Zone NP25) Saint-Etienne d'Orthe Clay in the Aquitaine Basin, SW France. Notwithstanding the geographic distance separating both areas, 12 of the 20 nominal species (60%) recorded from the Eger area are also known from Saint-Etienne d'Orthe. Species from both the Eger and the Kiscell Formations are found together in the Saint-Etienne-d'Orthe association. This can be explained by the depositional environment of the Saint-Etienne-d'Orthe Clay (deep neritic to uppermost slope), the depth of which was intermediate between that of the two Hungarian Formations. It confirms that the marked difference between the Kiscell and Eger otolith associations is ecologically conditioned. Another very important conclusion is that the Late Oligocene (nannoplankton Zones NP 24 and 25) ichthyofauna must have been quite homogeneous from the Paratethys to the Eastern Atlantic. In the neritic component of the fauna studied, the ambassids, sillaginids and leiognatids have an exclusively Indo-West-Pacific Recent distribution (except for some recent Mediterranean intruders through the Suez Canal). Among the deeper dwelling neritic taxa and oceanic fishes, 10 genera or families are not represented in the Recent Mediterranean fauna. This proves that in the Late Oligocene, even marginal deep dependences of this basin were inhabited by more typical oceanic faunas than today. All these data fit very well with the paleogeographic reconstruction of the Late Oligocene Mediterranean realm by RÖGL & STEININGER, which postulates a Paratethys without direct link with the North Sea Basin, but with an open connection with an Indo-Pacific-Atlantic seaway across the Mediterranean and a pronounced circum-equatorial current system. Six new species are introduced: Rhechias nagymarosyi, Opisthoproctus stellaris, Xenodermichthys senesi, "genus Gonostomatoideorum" aenigmaticus, Diaphus pristismetallis, "genus aff. Raniceps" coelorinchoides