A retrospective study of 150 patients with acute renal failure (ARF) was conducted to assess the influence of both protein and caloric intake and non-renal complications on the prognosis, as well as the predictive value of plasma protein levels. The majority of ARF had occurred in medical or surgical settings (46% and 32.7%, respectively). Nutritional data were available from 94 patients, fed either by parenteral or enteral routes, or both. The mean caloric intake was higher (29 kcal/kg/day) in patients who recovered than in those who did not (24 kcal/kg/day, p less than 0.01). A caloric intake above 35 kcal/kg/day resulted in an improved survival, independently of either patients' age or non-renal complications. Serum prealbumin and transferrin levels were higher in surviving patients than in those who died, 0.25 vs 0.16 g/l (p less than 0.001) and 1.7 vs 1.4 g/l (p less than 0.01), respectively. Nutritional support in ARF could be adapted according to the variations of these serum markers. Its influence on survival should be assessed with regard to the associated prognosis factors.