© 2020 Elsevier B.V.Seasonal and spatial distribution of Noctilucoid dinoflagellates collected from three stations (river mouth, coastal and offshore waters) were investigated between May 2015 and April 2016 in the SE Black Sea. Noctilucoid dinoflagellates were represented with four species, Noctiluca scintillans (Macartney) Kofoid & Swezy, 1921, Scaphodinium mirabile Margalef, 1963, Spatulodinium pseudonoctiluca (Pouchet) J.Cachon & M.Cachon, 1968 and Pronoctiluca pelagica Fabre-Domergue 1889. The abundance of Noctilucoids ranged between 0 and 575 cells l−1 in the first 100 m of the water column during study. Noctilucoid dinoflagellates comprised 0.0–48.5% of total dinoflagellate abundance in the study area with the highest percentages occurring in May 2016. Noctiluca scintillans was the most abundant species being associated with 45.6% of total Noctilucoids followed by P. pelagica (30.8%), S. mirabile (13.3%) and S. pseudonoctiluca (5.9%). There were no significant differences on Noctilucoid distribution between stations (p>0.05, one-way ANOVA), however significant differences were found between sampling dates with the highest in May (p<0.05, t-test). S. mirabile and S. pseudonoctiluca were reported for the first time from the Southeastern Black Sea.