Interleukin 17 (IL17) family is members of cytokines and functions as a pro-inflammatory factor secreted by activated T-cells. There are several members in IL 17 family, including IL 17A, IL 17B, IL 17C, IL 17D, IL 17E and IL 17F. These cytokines are similar in structure, sequence and function. The cognate receptors for the IL 17 family identified are consisting of IL17R, IL17RH1, IL17RL (receptor like), IL17RD and IL17RE. However, the ligand specificities of many of these receptors are still indistinct. The IL 17 family functions in kinds of tissues, such as brain, articular cartilage, lung, meniscus, intestine, hematopoietic tissue, bone, kidney and skin. IL 17 family members are essential participants in various arms of the adaptive immune response and are the key to understand cytokine networks which coordinate innate and adaptive immunity to certain pathogens. So the IL 17 family members may affect health effectively.