Polyamines as a very interesting vital compounds are present in all living organism including animals, plants, microbes and human. This book introduces what are the polyamines and their biological effect in the broiler chicken's body. The most important function of polyamines is their effects on cell growth, differentiation and normal functioning of every cell-type. Luminal polyamines are important local factors for growth and the development of small intestinal and colonic mucosa. Additionally, the effects of polyamines on calcium homeostasis are accomplished via the activation of calcium sensing receptors.