This research describes the qualitative and quantitative of food composition of the ctenophore Mnemiopsis leidyi, as well as its feeding intensity and predatory impact on selected mesoplankton species in the inshore waters of the southern Caspian Sea. The ctenophore Mnemiopsis leidyi initially increased during initial years, and during recent years its population and biomass reached at a low level. The highest average of M. leidyi abundance was found in summer-autumn months.