Objective: Nutritional support and the route of nutrition are important conditions for patients with acute renal failure (ARF) in intensive care units (ICUs). Enteral nutrition (EN) is the primary route of nutrition in these patients because of a lower rate of complications. A lack of enteral feeding was reported to increase intercellular adhesion molecule-1 (ICAM-1) in experimental models. Serum soluble ICAM-1 (sICAM-1) level is an independent predictor of mortality in predialysis patients. However, the effect of nutritional route on serum ICAM-1 level is unknown in ARF patients. The aim of this study was to investigate the relationship between route of nutrition and serum ICAM-1 level and its prognostic implications in ICU ARF patients. Methods: In total, 64 ICU patients with ARF were assessed according to their clinical features, route of nutrition, laboratory parameters, serum sICAM-1 levels, presence of infection, Acute Physiology and Chronic Health Evaluation (APACHE) III scores, and outcomes on their first nephrology consultation day. Results: Thirty-two patients died during the follow-up period. The mortality rate and infection rate were higher in the parenteral nutrition (PN) group compared with the EN group (64% vs 42%, P = .05, and 84% vs 64%, P = .05, respectively). The route of nutrition influenced the serum sICAM-1 level. Parenteral nutrition was associated with a higher serum sICAM-1 level compared to EN (434 ng/mL [range 255 to 1,240] vs 217 ng/mL [range 123 to 296], respectively, P = .0004). The APACHE III score was found to be an independent prognostic factor among the parameters of nutritional route, presence of infection, serum albumin level, and serum sICAM-1 level. Conclusions: Patients with ARF as supported by PN had a lower serum albumin level, and a higher APACHE III score, sICAM-1 level, and mortality and infection rate. Serum sICAM-1 levels did not independently predict mortality in the present set of ARF patients. © 2008 National Kidney Foundation, Inc.