Temperature plays an important role in vertical distribution of zooplankton especially in summer. Zooplankton samples were collected vertically at different depths in the main channel of Lake Nasser in front of Khor Kalabsh during July, 2007. The highest density of zooplankton (63779 Organisms/m3) and the highest number of species (10) was recorded between 2-5 m with an average temperature of 30.21°C. The surface water layer recorded the second most abundant zooplankton (47222 Organisms/m3) with temperature (34.8 °C). This is due to the highest abundance of Brachionus calciflorus (14444 Organisms/m3). Also, B. calcifloris recorded high number from 0-2 m (10508 Organisms/m3) and not recorded at any other water layer (up to 20 m depth). This indicates that this species is thermophilic which is supported by the highest positive correlation (0.79) with temperature. Keratella tropica was recorded only between 15-20 m with an average temperature of 21.88 °C.