Gut can be a source of sepsis but sepsis itself can induce gut dysfunction. We aimed to study whether plasma citrulline, a marker of enterocyte mass, was correlated with plasma lipopolysaccharide, a potential marker of bacterial translocation among critically ill patients. Critically ill patients admitted to the ICU. Plasma citrulline and plasma LPS concentration and activity were measured at ICU admission. Patients were compared according to the presence of sepsis at ICU admission. 109 critically ill patients, with SOFA score 8 6–12, were prospectively included. Sixty six patients (61%) had sepsis at ICU admission. There was no correlation between plasma citrulline concentration and plasma LPS concentration or activity. However, sepsis at ICU admission was associated with a lower plasma citrulline concentration (13.4 μmol.L−1 vs 21.3 μmol.L−1, p = 0.02). Plasma LPS activity was significantly higher among patients with abdominal sepsis compared to patients with extra-abdominal sepsis (1.04 EU/mL vs 0.63, p = 0.01). Plasma citrulline is not associated with the level of plasma LPS but is strongly decreased among septic patients. Detection of LPS is ubiquitous among critically ill patients but abdominal sepsis is associated with increased plasma LPS activity compared to extra-abdominal sepsis. •Plasma citrulline concentration was not correlated with circulating LPS among critically ill patients admitted to the ICU.•Sepsis was associated low plasma citrulline concentration suggesting a reduced enterocyte mass.•Abdominal sepsis was associated with higher plasma LPS activity compared to extra-abdominal sepsis.•Sepsis was associated with increased PLTP activity suggesting a possible LPS detoxification by the liver.