Interleukin 18 (IL-18) is a recently identified cytokine, originally called interferon gamma inducing factor. Due to its capacity to induce interferon gamma production in Th1 type cells. It has pleiotropic biological functions. IL-18 belongs structurally to the IL-1 cytokine family and shares biological properties with IL-12. Consequently, IL-18 is a potential regulator of antitumor immune response. IL-18 plays an important role in autoimmune disease and endotoxin-induced injury. So, future work will focus on its application as an immunotherapeutic agent for a variety of diseases.