Quantitative and qualitative examinations of zooplankton in Aslantaş Dam Lake were studied between April 2001 and March 2002. It was established that total zooplankton in the reservoir is being represented with 18 species belonging to Cladocera and Copepoda. Number of the species belonging to cladocer and copepod are 14 and 4, respectively. Contrary to the number of species, abundance was found to be in favor of copepods (65.99% of total zooplankton). Remaining one third of total zooplankton (34.01%) was cladocerans. The most abundant species were determined as Bosmina longirostris among cladocerans and Thermocyclops vermifer persicus (Lindberg, 1936) among copepods. Monthly depth of light penetration zone (photic zone) was calculated using Secchi disk readings. It was observed that the copepods were more abundant than the cladocerans in the light penetration zone (photic zone). Beyond the light penetration zone the situation was reversed and the cladocerans were found to be more abundant than the copepods. Chlorophyll-a level was also examined in the lake. Since this study is the very first study carried out on the zooplankton of Aslantaş Dam Lake, all of the species observed are the first reports for Aslantaş Dam Lake.