Artificial nutrition in course of acute renal failure (ARF) is reviewed, on the basis of recent concepts on epidemiology and prognosis of the syndrome in critically ill patients. The relationships between nutritional status and ARF are evaluated, analyzing the possible role of nutritional status alterations as comorbidities and complications; pathogenetic mechanisms and consequences of hypercatabolism are described, with special regard to the peculiar metabolic derangements which are the hallmark of ARF. The effects of artificial nutrition on mortality and morbility in ARF are illustrated, along with quantitative and qualitative aspects of nutritional support (energy and protein needs, trace elements, vitamins etc). A rational approach to nutritional management of ARF patients is proposed, stressing the potential role of enteral nutrition, as well as the need for a full integration between nutritional support and renal replacement therapies.