Abstract This study was carried out in order to determine population of zooplankton in the coastal waters of Gokgeada. At the 10 stations of those depths ranging from 20 in to 30 in, the measurements of temperature, salinity and oxygen were made, and zooplankton samples were collected vertically and horizontally using plankton nets. In the neritic waters of the island, the effects of the Black Sea waters through Dardanelles were observed and zooplankton species of the Black Sea found. From laboratory examinations of samples, it was de€grmined that the most important group of zooplankton was copepods. The number of Mnemiopsis leidyi, ctenophor, increased excessively during the periods of summer and autumn. Larger copepod species, such as Centropages typicus, Calanus helgolandicus, Ctenoealanus vanus, Anornalocera patersoni, appeared during winter and spring periods; however, Acartia clausi, which is considered as a indicator of polluted waters, was found to be abundant at every station all around the year. Relatively smaller species such as Corycella. rostrata, Oithona helgolandica, Euterpina acutifrons were determined in smaller numbers at most stations. Cladocers were observed at every period: of them, 'Penilia avirostris was found to be the most observed species. In the samples collected from 40 stations during the year, 51 species were determined.