The renin-angiotensin system (RAS), also known as the renin-angiotensin-aldosterone system (RAAS), is well known for its role in the regulation of blood pressure, volume fluid and capillary perfusion. It is one of the most important systems studied by those interested in the cardiovascular system and those involved in the pathogenesis of heart and kidney disease. The renin-angiotensin system exists in two frameworks: a circulating system and several local tissue-specific systems. Local RAS have been found in the pancreas, heart, brain, vessels, adrenal glands, and reproductive tracts (1). In the classical RAS pathway, the crucial hormone angiotensin (Ang) II is formed by cleavage of angiotensin I. The effects of Ang II are mainly exerted by two receptors: the angiotensin II type 1 receptor (AT1R) and the angiotensin type two receptor (AT2R). ). The physiological attributes and regulations of Ang II vary depending on the tissue. For example, brain RAS regulates thirst, salt appetite, sympathetic activation, and vasopressin release, while renal RAS regulates fibrosis and sodium retention. In this article, an overview of the components of the circulatory renin-angiotensin system and their productions will be given, as well as evidence supporting a cardiac RAS. The local RAS of the heart deviates from the classical pathway in two ways, one being other sources of production such as myocytes and fibroblasts which differ from the renal or neural RAS, and the other being its functions and roles which distinguish it from other tissue RAS. According to research conducted, the renin-angiotensin system is an essential element that contributes to the progression of heart failure (2). This prompted further research into suppressing the RAS to control the rate of...... middle of article ...... (December 6, 1999) The renin-angiotensin-aldosterone system: a target specific for hypertension management. Am. J. Hypertens. 10.1016/S0895 7061(99)00103-X7. Danser, AHJ, Saris, JJ, Schuijt, MP and van Kats, JP (June 10, 1999) Is there a local renin-angiotensin system in the heart? Cardiovascular. Res. 10.1016/S0008-6363(99)00202-38. Kumar, R., Singh, VP and Baker, KM (April 2009) The intracellular renin-angiotensin system in the heart. Curr. Hypertensives. Report 10.1007/s11906-009-0020-y9. Shearer, F., Lang, CC and Struthers, AD (September 11, 2013) Renin-angiotensin-aldosterone system inhibitors in heart failure. Clin. Pharmacol. There. 10.1038/clpt.2013.13510. Abadir, PM, Walston, JD and Carey, RM (September 29, 2012) Subcellular characteristics of functional intracellular renin-angiotensin systems. Peptides. 10.1016/j.peptides.2012.09.016