The main physiological role of the renin angiotensin aldostrone system (RAS) is to regulate blood pressure and water balance. It contains a group of related hormones that act together and called as angiotensins, receptors and enzymes. This system plays an important role in the pathology of many diseases. That’s why the blockage or stimulation of the components of RAS have important clinical applications. In this review we have tried to summarize recent findings about RAS.