The aim of this study was to assess the zooplankton community in Danube branches to determine the water quality from this point of view. For this was studied 12 sampling sites: Cotul Pisicii, downstream Reni, Ceatal Chilia, downstream Izmail, Periprava, upstream Bastroe channel, downstream Bastroe channel, Ceatal Saint George, upstream Sulina, downstream Sulina, upstream Saint George, downstream Saint George for the sampling period -21 March - 2 April, 2019. The preliminary results of the analysis of the biotic community of zooplankton determined from all 12 locations demonstrated the following aspects: The zooplankton of the RBDD flowing ecosystems is characterized by reduced diversity, small numerical abundances and low biomasses. During the study period various species of Rotifers, Copepods, Cladocerans were recorded, in all samples total 30 species of zooplankton were identified, 3 species of Cladocerans, 5 species of Copepods and 22 species of Rotifers. The zooplankton community was dominated by Copepoda, which contributed about 50% to the total zooplankton density. Overall, oligo-mesosaprobic - Keratella quadrata, Notholca squamula to beta-mesosaprobic rotifers - Polyarthra vulgaris, Pompholyx sulcata, Brachionus angularis bidens have been prevailing indicating that the water was slightly or moderate polluted. A higher number of species and numerical abundances was recorded in downstream comparatively to upstream sector, this may be attributed to the gradual decrease of the flow rate of the water. The researches will be continued in order to assess the seasonal variations and to estimate the role of zooplankton community as indicator of changes in water quality along DDBR, flowing ecosystems.