Well-preserved Lower Sarmatian (Elphidium reginum Zone) foraminifera fauna from an open working pit at Ludovika square, four boreholes and a ventilation tube of the subway (line #3) in Budapest were studied. Detailed systematic descriptions and paleoecological interpretation (together with the ostracod fauna) of 28 taxa are provided. Three biofacies (with Elphidium, with Cibicides, with Articulina and Nodophthalmidium) could be distinguished. These different foraminiferal biofacies and ostracod faunas show the changes of an epiphytic community that was influenced by the phytal substrates, the water depth, the nutrient and oxygen content and the salinity. The changes in the abundance of foraminifers and ostracods indicate distinct changes in the vegetation (algae to seagrasses) reflecting decrease of the water-depth and salinity during the Early Sarmatian in this region of the Central Paratethys. The studied foraminifera fauna is most similar to the foraminifera assemblage from the Zsámbék Basin (Hungary) and to the assemblages of the Eastern Paratethys due to the lack of buliminids in the other region of the Central Paratethys
