It is now well established that the activation of the renin-angiotensin system (RAS) is involved in the onset and progression of cardiovascular and renal diseases, and that its main effector, angiotensin II (Ang II) has major pro-inflammatory activity that induces the expression of cytokines, chemokines, adhesion molecules, growth factors and reactive oxygen species. By means of these actions, Ang II induces vascular inflammation, endothelial dysfunction and fibrosis, and participates in destabilizing atherosclerotic plaque and establishing chronic kidney diseases. Blocking the RAS by inhibiting Ang II generation or blocking angiotensin receptors reduces the morbidity and mortality associated with cardiovascular and renal disease beyond the levels due to the lowering of blood pressure, and these benefits are at least partially due to the reduction/prevention of both local and systemic inflammatory processes. The aim of this review is to describe the role of the RAS (and particularly Ang II) in initiating and maintaining these processes, and to summarize experimental and clinical evidence supporting the role of drugs acting on the RAS in preventing or modulating inflammation.