Interleukin 18 （IL-18） is a pleiotropic cytokine involved in the regulation of innate and acquired immune response. In the milieu of IL-12 or IL-15, IL-18 is a potent inducer of IFN-gamma in natural killer （NK） cells and CD4 T helper （Th） 1 lymphocytes. However, IL-18 also modulates Th2 and Th17 cell responses, as well as the activity of CD8 cytotoxic cells and neutrophils, in a host microenvironment-dependent manner. IL-18 is a cytokine that stimulates various cell types and has pleiotropic functions. Recently, IL-18 has also been shown to execute specific effects in pancreatic diseases, including acute and chronic pancreatitis, as well as pancreatic cancer.