In modem poultry husbandry, the high population densities in a manmade artificial environment pose a considerable challenge for the immune system to compensate non-infectious and infectious factors. Therefore, the integrity of a functioning immune system is of paramount significance to safeguard flock health and productivity. The use of chemical antimicrobials has led to concerns involving environmental contamination and unwanted residues in food products. The imminent banI).ing of antibiotic usage in livestock feed has intensified the search for environmentally-friendly altern~tive methods to control disease. Cytokines, as natural mediators and regulators of the immune response, offer exciting new alternatives to conventional chemical-based therapeutics. Cytokines are proteins secreted by cells that play an important role in the activation and regulation of other cells and tissues during inflammation and immune responses. Although well described in several mammalian species, the role of cytokines and other related proteins is poorly understood in avian species. Although the study of cytokines and chemokines in avian species is still in its infancy when compared to that of mammals, huge strides have been made in recent years. Cytokines playa vital role in the development of immunity to a range of infections, and their use as therapeutics in both infectious and non-infectious disease is likely to be investigated in greater depth and with a larger range of cytokines. Their potential use as adjuvants, particularly incorporated within DNA vaccines or vaccine vectors, is also being investigated. These new generation delivery mechanisms also allow the administration of single or multiple cytokines, in combination with vaccine antigens. The choice of particular viruses will allow antigen and cytokine targeting to specific sites such as gut, thereby allowing the most appropriate type of immune responses to be generated. In this review the authors will discuss about avian immune system and the functions of avian cytokines, the main types of cytokines so far found in the chicken and their potential as adjuvants or therapeutic agents.