Protein-calorie malnutrition affects a large fraction of patients with end-stage renal disease (ESRD) and contributes significantly to the high rates of mortality and morbidity observed in this population. Observational studies of specific interventions, including intradialytic parenteral nutrition (IDPN), suggest that aggressive nutrition support may be of some benefit to some patients with ESRD. Due in part to lack of data derived from prospective, randomized clinical trials, and to the large expense associated with these therapies, Medicare and other payers have strongly discouraged the prescription of IDPN and other intermittent, dialysis-specific methods of nutrition support, such as intraperitoneal nutrition (IPN). The "burden of proof" has been placed on the dialysis community. In response, we must continue to emphasize the importance of securing nutritional health for all patients on or anticipating renal replacement therapy. Intradialytic parenteral nutrition should be reserved for patients who are taking in sufficient calories yet are unable to tolerate oral or enteral protein-rich foods or formulas designed to meet daily protein requirements (> or = 1.5 g/kg in some patients). Intradialytic parenteral nutrition should not be prescribed in place of total parenteral nutrition (TPN) if the latter is truly needed. Creative methods of nutrition support, including the use of dietary supplements at dialysis (intradialytic oral or enteral nutrition), should be explored. Prospective clinical trials investigating the effects of nutrition support on survival, hospitalization rates, health-related quality of life, and functional status, are urgently needed.