The kidneys perform a wide array of functions in the body, most of which are essential for life. Regulation of water and electrolytes, excretion of metabolic waste and of bioactive substances like hormones, drugs etc., which affect bodily functions; regulation of arterial blood pressure, red blood cell and vitamin D production; are some of the major functions that the kidneys perform. It is obvious then, that patients with renal failure present a steep challenge to the physician taking care of this special population. Renal replacement therapy remains only a part of treatment that helps substitute the regulation of water and electrolytes, removal of metabolic waste, and to a certain extent removal of drugs and other bioactive substances from the body. This article aims to provide an understanding of different types of renal replacement therapy, mainly to patients with end-stage renal disease (ESRD).