The renin-angiotensin system (RAS) is a major hormonal system that plays an essential role in regulating salt-water balance and blood pressure. In this book, the authors discuss the physiology, role in disease and health implications of RAS. Topics include the function of the renin-angiotension-aldosterone system in ISIAH rats with stress-sensitive arterial hypertension; RAS implications for eye diseases, obesity and diabetes, and cardiovascular disease; intensive blockade of renin-angiotensin systems; glomerular renin-angiotensin system activation; the role of vitamin D in RAS; the renin-angiotensin system in the pathogenesis of intracranial aneurysms; and a discussion on whether angiotensin-converting enzyme inhibitors are a contradiction for contrast-induced nephropathy prophylaxis?