The renin-angiotensin-aldosterone system (RAAS) plays a relevant role not only in the pathophysiology of essential hypertension, but also in the development of hypertensive target organ damage. Different drugs acting on RAAS components are now available: angiotensin-converting-enzyme (ACE) inhibitors, angiotensin II AT1 receptors blockers (ARBs), non-selective and selective aldosterone antagonists. The review will focus on their effects on hypertensive organ damage. In fact, apart from the well known efficacy in reducing blood pressure, all these drugs have been demonstrated to protect against target organ damage, reversing or preventing its development. The main issues addressed will be: effects of the RAAS blockade on heart and kidney disease, protective action against arterial wall damage, with a focus on the endothelial protection. The comparison among ACE inhibitors, ARBs and aldosterone antagonists will be discussed, with specific reference to different class and/or drug effects and to the results of few studies evaluating the effects of combination therapy with different drugs blocking the RAAS.