Phytoplankton data collected in the Black Sea, Bosphorus area, Marmara Sea, Aegean Sea, Ionian Sea, Tunisian Strain, and Mediterranean Sea during 65 cruise of the R/V "Kovalevskiy" and processed by Lyudmila Georgieva. <br> The samples were taken with 6 liter bathometers at standard depths and in the thermocline layer. The standard sedimentation technique for samples preparation (Usachev, 1926) was used. Samples were preserved by buffered formalin 40% and were settled within 30 days. Then a volume of water was siphoned off and samples were concentrated to 10-20 ml. After thorough mixing the subsamples (0.05 or 0.1 ml) were transferred to the counting chamber. Organisms were counted in two subsamples at ×300 - 400 magnification.