Abstract. The present paper deals with the geology and the paleontology of the Baraolt and Sf. Gheorghe Basins, that are part of the Brasov Depression lying in the south-eastern part of Transylvania. This structural depression represented a big lacustrine basin almost during the whole Pleistocene. The deposits were laid down on a Mesozoic floor and are to be divided into four horizons in accordance with a same number of phases of the basin developement. Mammalian faunas of these horizons were grouped into three main complexes corresponding to the Lower, Middle and Upper Pleistocene. The first faunal complex comprises two phases, the second three and the last only one.