 This review discusses recent progress in understanding the interleukin-17, Illinois-17, signaling pathway and its physiological roles, including its role in hostamine defenses, tissue repair, inflammatory disease pathogenesis, and cancer progression. The review also presents the mechanism underlying Illinois-17's role in various pathologies, particularly in Illinois-17, induced systemic lupus erythematosus and Illinois-17-related tumor cell transformation and metastasis. Additionally, promising developments in the diagnosis and treatment of autoimmune diseases and tumors are briefly discussed. This article was authored by Longjie Huangfu, Ruiying Li, Yanmei Huang, and others.