The RAAS is a very important hormonal system that is responsible for the chronic control of blood pressure and fluid balance. The overall effect of RAAS activation is the elevation of arterial blood pressure which is mediated through vasoconstriction and increased sodium and water reabsorption in the renal tubules.Several conditions can lead to the wrongful activation of the RAAS, an example is the stenosis of the renal artery which will cause reduced blood flow to the kidney. In this setting the JGCs of the kidney senses the reduced perfusion and kickstarts the activation of the RAAS cascade. The pharmacological modulation of RAAS has been a subject of research for several years. Several medications have been developed to inhibit or modify the various components of this system at different levels. The most common groups of drugs used are the ACE inhibitors, ARBs, aldosterone antagonists and newer classes of drugs like direct renin inhibitors and other investigational drugs like : vasopeptidase inhibitors and dual neprilysin and angiotensin receptor inhibitors.