This study was carried out to determine seasonal variation and zooplankton community structure in Karataş Lake, Southern Turkey. Zooplankton samples were collected seasonally between 2002 and 2003 in two stations using a zooplankton net of 55-µm mesh size. A total of 42 taxa were identified, including 19 taxa (45.2%) Rotifera, 16 taxa (38.1%) Cladocera, and 7 taxa (16.7%). Copepoda. Among them, Keratella quadrata, Asplanchna priodonta from Rotifera, Daphnia longispina, Ceriodaphnia quadrangula, Chydorus sphaericus, Coranatella rectangula from Cladocera, and Eudiaptomus drieschi, Eucyclops speratus from Copepoda were dominant species. Spring and autumn seasons were found to be the most similar by using Sorenson index value.