Chronic kidney disease is a worldwide public health problem with an increasing incidence and prevalence, poor outcomes, and high cost. Outcomes of chronic kidney disease include not only kidney failure but also complications of decreased kidney function and cardiovascular disease. Current evidence suggests that some of these adverse outcomes can be prevented or delayed by early detection and treatment. Residual renal function among patients with end stage renal disease is clinically important as it contributes to adequacy of dialysis, quality of life, morbidity and mortality. The preservation of residual renal function (RRF) is important after initiating dialysis, as well as in the pre-dialysis period. Longer preservation of RRF provides better small and middle molecule removal, improved volemic status and arterial pressure control, diminished risk of vascular and valvular calcification due to better phosphate removal. Deterioration of RRF results in worsening of anemia, inflammation and malnutrition. A direct relationship between RRF value and survival in dialysis patient. is now proved.