The nutritional situation of patients with end-stage renal failure is very heterogeneous. There is no uniform “kidney diet”: The demand of nutrients and fluid varies greatly, depending on age (infants, children, adolescents, adults), current body composition, mode of dialysis, underlying disease, concomitant diseases and residual diuresis. End-stage renal failure substantially interferes with the major regulators of appetite and energy expenditure, namely, leptin and ghrelin. Loss of appetite, waste of important nutrients by dialysis and chronic inflammation promote a state of catabolism in end-stage renal disease patients. Acute life-threatening conditions may occur in cases of excessive hyperhydration and hyperkalemia. The most important aims of nutritional modifications are prevention of hyperhydration and cachexia but nowadays also adiposity, electrolyte disorders, disturbed bone metabolism and cardiovascular complications. In infants, children and adolescents the underlying disease and varying age requirements determine the nature of nutritional dysregulation as well as the resulting management. It is most important to achieve an adequate growth and development of the patients. Guidelines on nutrition in renal failure are available from the National Kidney Foundation of the United States and the European Dialysis and Transplant Nurses Association/European Renal Care Association. It is the objective of this chapter to review the pathophysiological changes of appetite and nutrition in end-stage renal failure with a special focus on children and adolescents.