THE SPECTRUM of clinical disturbances that characterize renal failure results primarily from an imbalance between excretory capacity and the intake of nutrients. For many ingested substances, intake becomes excessive in the patient with renal failure, leading to accumulation with resulting clinical disturbances and also to compensatory responses that often have their own deleterious side effects. For other ingested substances, intake may become inadequate because of renal wastage, increased requirements, or overzealous dietary restriction. Thus, the goal of nutritional management in renal failure is to adjust the intake of nutrients to meet the profoundly altered needs and capacities of the patient. If this goal could be achieved, many of the clinical disturbances seen in renal failure could be relieved. Nonexcretory functions of the kidney are also impaired in renal failure. Among these are the hormonal functions of the kidney, such as its role in hormonal excretion and degradation, blood pressure regulation, erythropoiesis, and vitamin D activation. Impaired substrate-fuel functions of the kidney also contribute to the uremic state, such as alterations in amino acid metabolism and gluconeogenesis. Correction of these abnormalities is more difficult, and often not possible by nutritional management. Nevertheless, these abnormalities significantly modify the strategy of nutritional therapy in such patients. In the patient on chronic dialysis, a different spectrum of problems may emerge. Many, but by no means all of them are nutritional. They are not generally the result of imbalance between intake and excretory capacity, since they may persist even when excretory capacity is increased by more frequent dialysis. They may arise from the failure of non excretory functions of the kidney, from the accumulation of trace substances derived from the dialysis water, or from the removal by dialysis of important constituents of body fluids. For discussions of the relationship between nutritional management and the particular techniques and schedule of dialysis, the reader is referred elsewhere. 1-6 Conservative nutritional management in the predialysis stage may in some cases slow progression of renal insufficiency (as measured by the rate of decline of glomerular filtration rate). The aspects of management that are most important in this respect and the results that can be achieved in different types of renal disease are as yet ill defined. However, the obvious merit of slowing or halting the progression of renal failure, especially when compared with the difficulties and expense of dialysis and/or transplantation, makes this an area of high priority for investigation.