Zooplankton refers to the weak swimming animals or those which move under the mercy of water current. They occupy a central position in the food chain in the aquatic ecosystems between primary producers and higher consumers. Zoo-plankton plays an important role in a lake's ecosystem and food chain. Unlike algae, or phytoplankton, zoo-planktons are microscopic animals that do not produce their own food.The need for such a book arises from the fact that few previous attempts were made to record zoo-plankton in the North West region of Saudi Arabia. In addition that the region can be considered as a unique habitat in its characteristics as an arid habitat. The nature of the habitat is mainly desert and the majority of the investigated sites were temporary lakes or ponds. So, the authors of the book hope that this work will initiate future works in this field in Tabuk and other regions of the Kingdom of Saudi Arabia to cover the whole region.