To determine its relationship with acute cholangitis (AC), we sought to quantify expression of triggering receptor expressed on myeloid cells (TREM-1) in peripheral blood mononuclear cells (PBMC) of sepsis patients with AC. Peripheral blood samples of 42 AC patients and 48 patients with AC of severe type (ACST) were collected from January to September, 2008 and tested for TREM-1 mRNA by RT-PCR and protein expression by immunocytochemistry and Western blotting. ELISA and immunoturbidimetry were employed to detect the changes of TNF-α or C-reactive protein in the serum respectively. TREM-1 expression was higher in ACST group than in AC group (P<0.01). TREM-1 was positive in mononuclear cells by immunochemistry in both groups before operative therapy, but the positive expression rate decreased at 48 h postoperatively. Compared with healthy controls, TREM-1 protein expression levels were up-regulated in sepsis patients with AC. TREM-1 expression has highly sensitivity and specificity in sepsis patients with AC or ACST. TREM-1 is up-regulated in PBMC of AC patients, and has higher sensitivity and specificity than other clinical inflammation markers, suggesting its importance in AC-induced sepsis.