Recent investigations of the Upper Badenian and Sarmatian of the Transylvanian Basin revealed particular, small sized planktonic foraminiferal assemblages. SEM investigation permitted more precise taxonomic interpretations of the planktonic species. The Late Badenian assemblage — with trochospiral, microperforate, and pustulose Tenuitellinae — occurring in relation to a transgressive event close to the end of the Badenian, makes possible an increased biostratigraphic resolution. The Sarmatian assemblage with Streptochilus (biserial Chiloguembelinidae) provide evidence for the paleogeographic connections to the Indo-Pacific area, and support new paleoenvironmental and biostratigraphic interpretations.