The Oligocene-Miocene boundary in the Central and Eastern Paratethys is indicated by the appearance of numerous globigerinoides, Miocene nannoplankton and the disappearance of cavate cysts. In the studied sections this boundary coincides with the tops of Lower Krosno and Middle Menilite ”subformations” of the Ukrainian Carpathians, Chernobayev Formation of the Northern Black Sea area and the Caucasian regional stage of the Northern Caucasus.