Zooplankton samples were taken for determination of the zooplankton fauna of the lower Euphrates basin (between Birecik Dam Lake and Karkamış Dam Lake). In the study, 10 families from Rotifera, 6 families from Cladocera and 4 families from Copepoda, totally 20 family were found. A total of 41 zooplankton species were identified. From Rotifera, Lepadellidae was the most species rich family with 4 species, from Cladocera, Daphnidae was the most species rich family with 4 species and from Copepoda, Cyclopoidae was the most species rich family with 7 species.