The early Miocene mollusc faunas from the Proto-Mediterranean Sea are still poorly-known. Herein, Aquitanian gastropod assemblages from the Felli section in NW Greece are described. Two assemblages were recovered, a low-diversity coastal mudflat assemblage dominated by Granulolabium plicatum (Bruguière, 1792) and Mesohalina margaritacea (Brocchi, 1814), and a high-diversity marine assemblage dominated by Bittium larrieyense (Vignal, 1911). The marine assemblage yielded 44 species, of which three species are described as new and 23 are left in open nomenclature. A new combination is proposed for Finella perpusilla (Grateloup, 1827). The family Pyramidellidae is exceptionally represented by 15 species. 17 new occurences are reported for the Proto-Mediterranean Sea. Alvania amphitrite n. sp., Homalopoma acaste n. sp. and Pyramistomia aliakmoni n. sp. are introduced as new species.