Introducing valuable data about the different veterinary protozoa, especially those endemic in Egypt, and getting to know them Ocular and microscopic description of these protozoa. Identifying the various diseases caused by these protozoa .the pathological manifestations methods of diagnosis, treatment and control of different disease caused by protozoa.The underlying principle of pathology is that all disease processes have a cellular basis, or, stated more simply, all disease is due to cell injury. Changes in the arrangement, structure, or products of cells are of fundamental importance in diagnostic pathology.Cellular injury can be lethal (fatal), causing necrosis, or cell death. It can also be sublethal, meaning the cell or tissue function is altered but the cell isn't destroyed. Deterioration of cell function can occur following nonlethal cell injury.This alteration is referred to as cell degeneration.