The renin-angiotensin system (RAS) has long been seen as a systemic endocrine system in which angiotensin II (ANG II) is solely involved in blood pressure regulation and the mediation of aldosterone release. However, it is now known that specific organ systems exhibit their own local RAS, functioning for the most part independently from their systemic counterpart. A deluge of data from the last decade has shown that ANG II displays many more functions than just regulating blood pressure: ANG II is a growth factor, exhibits profibrogenic actions, and even serves as a proinflammatory cytokine. It is now clear that this peptide plays a pivotal role in the progression of chronic kidney disease towards endstage renal failure. Clinical studies have provided compelling evidence that interference with ANG II slows this deterioration of renal function. This publication presents the first comprehensive summary of this important topic: Basic concepts as well as clinical aspects of the RAS are reviewed by international experts who made many of the key discoveries that constitute our contemporary understanding of ANG II as a central factor in the progression of renal disease. This publication should be read by physicians treating patients with chronic renal diseases (internists, nephrologists and urologists). Moreover, basic scientists such as renal physiologists, renal pathologists and biochemists who want a comprehensive overview of the subject will profit from reading this book.