Résumé : Purpose Increased bilirubin concentrations may be related to outcome, but this has not been well studied. We evaluated the relationship between total serum bilirubin levels and outcome in critically ill patients. Materials and methods Data were analyzed from adult critically ill patients included in a 1-day international prevalence study after excluding those with an obvious underlying cause of hyperbilirubinemia. Results Serum bilirubin concentrations were >1 mg/dL in 2803 (31%) of 8973 patients, and these patients had higher mortality rates than patients with lower bilirubin concentrations (30% vs 21%, P < .01). For serum bilirubin values of 1.1-6 mg/dL, there was a linear increase in crude mortality (R2 = 0.96), with the highest hospital mortality (42%) in patients with bilirubin concentrations between 3.7 and 6.0 mg/dL. There was no further increase in the mortality rates for patients with bilirubin concentrations >6 mg/dL. A serum bilirubin concentration >1 mg/dL was an independent risk factor for mortality in multilevel analysis. Conclusions Hyperbilirubinemia without a recognized cause was common and independently associated with increased mortality. There was a linear correlation of mortality with bilirubin concentration for values between 1 and 6 mg/dL but not for higher values.