Purpose: Early diagnosis and assessment of the systemic inflammatory response to infection are difficult with usual markers (fever, leukocytosis, C-reactive protein [CRP]). Triggering receptor expressed on myeloid cells-1 (TREM-1) expression on phagocytes is up-regulated by microbial products. We studied the ability of soluble TREM-1 (sTREM-1) to identify patients with sepsis. Materials and Methods: Plasma samples were obtained on intensive care unit admission from patients with systemic inflammatory response syndrome for sTREM-1 measurement. Results: Soluble TREM-1, CRP concentrations and erythrocyte sedimentation rate (ESR) were higher in the sepsis group (n - 52) than in the non-infectious systemic inflammatory response syndrome group (n - 43; P - .00, .02, and .001, respectively). Soluble TREM-1, CRP concentrations, white blood cell count and ESR were higher in the sepsis group than in the non SIRS group (n = 37; P = .04, .00, .01, and .00, respectively). In a receiver-operating characteristic curve analysis, ESR, CRP and sTREM-1 had an area under the curve larger than 0.65 (P = .00), in distinguishing between septic and non-infectious SIRS patients. CRP, ESR, sTREM-1 had a sensitivity of 60%, 70% and 70% and a specificity of 60%, 69% and, 60% respectively in diagnosing infection in SIRS. usion: C-reactive protein and ESR performed better than sTREM-1 and white blood cell count in diagnosing infection. (C) 2010 Published by Elsevier Inc.