This book focused on the important role of essential amino acid arginine in improve productive and physiological performance of broiler chickens. In these fields this book contain many chapters as regards the importance of this essential amino acid which included historical review of arginine,arginine composition, arginine metabolism, source of arginine, requirements of arginine to lysine ratio, physiological effect of arginine, cardiovascular effect of arginine, hormonal secretions of arginine, arginine effects on broiler performance and effect of arginine on certain physical and biochemical traits of blood . However,the book also focused on determine the effect of dietary supplementation with different levels of arginine on many criteria of productive performance, quality characteristics of carcass, physical traits of blood and biochemical traits of blood of broiler chickens. Finally, the authors concluded that dietary supplementation with different levels of L-arginine (0.02% , 0.04% and 0.06 %) resulted in significant improvements with relation to productive and physiological performance of broiler chickens.