Our data clearly suggest that assaying the soluble form of TREM-1 in plasma samples from newly admitted critically ill patients with suspected sepsis may be a valuable new approach to accurately diagnosing infectious processes. Early identification of infection has a major effect on the clinical course, management, and outcome of critically ill patients. Critical care physicians have a variety of indicators to help them discriminate infectious from noninfectious conditions in newly admitted patients. In some cases, the diagnosis of sepsis becomes clear after the medical history and physical examination are completed (20). In other circumstances, when noninfectious insults (for example, trauma, hemorrhage, burns, and pancreatitis) cause the systemic inflammatory response syndrome, diagnosis of sepsis remains challenging. Efforts have therefore been made to identify a reliable marker of infection. However, to date, no single clinical or biological indicator of sepsis has gained widespread acceptance (7, 21). Among the potentially useful markers, procalcitonin has been proposed as the most promising (6–8), but several authors have challenged this (9–11).