Interleukins are broad of small proteins that are important in cell signaling, health, and disease. Also, ILs are a large group of immune-modulatory proteins that elicit a wide variety of responses in cells and tissues. The role of interleukins in the pathogenesis of cardiovascular diseases is increasingly evident since the identification of inflammatory mechanisms in atherosclerosis and heart diseases. Moreover, diabetes is an inflammatory disease, numbers of interleukins have been shown to be important for the development of diabetes. Interleukin-17 (IL-17) is the founding member of an emerging family of inflammatory cytokines, which modulates immune cell trafficking and is involved inflammation in (auto) immune and infectious diseases. Now, there is evidence that targeting certain interleukins has led to clinical benefit, and so cytokines can be good therapeutic targets. Therefore, this book aimed to provide physician, scientists and medical students in the health professions with a concise resource that will help them to understand and appreciate the role of cytokines, especially interleukin-17 in the etiology, progression and complications of atherosclerosis and diabetes.