Résumé : Objective: The aim of this study was to assess the correlation between plasma citrulline and Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, survival, inflammation (C-reactive protein [CRP]), inotrope use, serum levels of prealbumin and albumin, and renal failure in the critically ill patient. Methods: This prospective observational singlecenter controlled study included 91 adult patients over a 2-year period. Inclusion criteria were patients staying in the intensive care unit for >48 hours. Patients renal status was categorized as those with a glomerular filtration rate (GFR) >60 mL/min without renal support, a GFR >60 mL/min with renal support, a GFR <60 mL/min without renal support, and a GFR <60 mL/min with renal support. Plasma citrulline concentrations were categorized into 3 groups: low (015 μmol/L), medium (1635 μmol/L), and high (>36 ?mol/L). The relationship between the recorded parameters and these different cut-off values of plasma citrulline concentrations was analyzed. Results: Ninety-one patients (34% female and 66% male) with a mean (SD) age of 69.3 (11.9) years, a mean (SD) body mass index of 24.8 (5.34) kg/m2, a mean (SD) APACHE II score of 22.4 (7.92), a mean (SD) SOFA score of 8 (4.4), and a mean (SD) plasma citrulline of 21.7 (13.1) μmol/L were enrolled. Only patients with intestinal dysfunction had low plasma citrulline level <15 μmol/L (P = .014). No correlations between serum levels of CRP, albumin, or prealbumin; renal failure; inotrope use; SOFA score; and APACHE II score were found with plasma citrulline level. Conclusion: Low plasma citrulline levels in patients correlate well with intestinal dysfunction. (Nutr Clin Pract. 2012;27:527-532) © 2012 American Society for Parenteral and Enteral Nutrition.