Tarkhanian calcareous nannoplankton in the area of Crimea have been studied in the sequence of Tarkhan s.str., new stratotype locality Maly Kamyshlak, Skelia section and in the Sokol-60 well (350.0–390.0 m). Associations of nannofossils are assigned to the zone NN5 and can be correlated with the calcareous nannoplankton associations of the Lower Badenian deposits of the Central Paratethys and the Langhian sediments of the Mediterranean area. Paleoreconstructions based on nannofossils have shown that at the beginning of the Tarkhanian transgression a warm sedimentary area with normal salinity was formed. It was connected with the basins of Western Paratethys and there is a possibility of connections with the Indian Ocean or Mediterranean Sea. Quantitative, as well as qualitative impoverishment of nannoplankton points to change of the basin regime, connected with strong terrigenous input, partial isolation and salinity decrease (the time of accumulation of Spirialis clays upper part).