The diet composition of Pleurobrachia pileus (Muller, 1776) was studied in five stations (Iyidere, Rize, Cayeli, Pazar and Findikli) located along the Southeastern Black Sea coast of Turkey. The diet of P. pileus was also investigated in relation to seasonal variations. Overall, the diet of P. pileus was dominated by prey groups from phytoplankton followed by zooplankton. Also, seasonal diet of P. pileus is exclusively dominated by phytoplankton only during autumn and winter periods. Dendrogram, multidi-mensional scaling plots, ANOSIM and SIMPER analysis indicated an extremely identical diet of P. pileus between spring and summer. Autumn and winter have distinct prey assemblages and revealed low diet similarities with the two other seasons. Such trend was not found between different regions indicating a similar diet. The study suggested that P. pileus is miscellaneous feeder and its diet composition may evince the availability of different prey groups in the ambient environment. The results obtained from this study would assess not only to describe the diversity of prey species to a certain extent but may also determine interspecific competition for food in the Southeastern Black Sea.