Coccidiosis is one of the most important protozoan diseases affecting the poultry sector all over the world. Coccidiosis is caused by the many species of Eimeria. They are typically intracellular parasites of the epithelial cells of the intestine of vertebrates. Cocidiosis can occur in all age groups of birds. Eimeria tenella is the most pathogenic than other species of Eimeria. Coccidiosis causes high mortality in chickens and this led to great economic loss to poultry sector. So, it is important to control the coccidiosis by better management in poultry houses, use of prophylactic coccidiostatic drugs and by vaccination of chickens.