Hemolytic anemia (HA) is a common condition in intensive care units (ICU) responsible for life-threatening organ failure in severe cases [1]. HA needs urgent treatment initiation, but its diagnosis remains challenging as none of the biological diagnostic parameters, including bilirubin, LDH and haptoglobin, are specific. During hemolysis, free hemoglobin released by red blood cells is catabolized by heme-oxygenase 1, leading to formation of iron, biliverdin and carbon monoxide [2]. Next, carbon monoxide binds to free hemoglobin to form carboxyhemoglobin. Carboxyhemoglobin is routinely measured in ICU and available within a few minutes by CO-oximetry, a point of care testing (GEM® Premier™ 4000, Werfen, Le Pré-Saint-Gervais, France) [3]. Our objective was to evaluate carboxyhemoglobin as a diagnostic tool for HA in adult patients admitted in ICU.