AIM: To investigate the probable role of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in the pathogenesis of inflammatory bowel disease (IBD). METHODS: Fifty-eight patients were enrolled; nineteen healthy volunteers served as controls; 8 patients were diagnosed with Crohn’s disease, and 31 with ulcerative colitis. Clinical and endoscopic activity indexes of patients with Crohn’s disease and ulcerative colitis respectively were estimated. Upon admission blood was sampled; sTREM-1 and TNFαwere measured by an immunoassay and malondialdehyde (MDA) by the thiobarbitourate assay, after passage through an HPLC system. RESULTS: Median±SE of TNFαof controls, patients with Crohn’s disease and patients with ulcerative colitis were 6.02±3.94, 7.98±5.08 (P = NS vs controls), and 8.45±4.15 ng/L (P = 0.018 vs controls) respectively. Respective values of sTREM-1 were 53.31±32.93, 735.10±197.17 (P = 0.008 vs controls) and 435.82±279.71 ng/L (P = 0.049 vs controls). sTREM-1 was positively correlated with Crohn’s disease activity index and clinical and endoscopic activity indexes of ulcerative colitis (P = 0.002, 0.001 and 0.009, respectively). sTREM-1 of patients with ulcerative colitis was positively correlated with TNFa (P = 0.001). CONCLUSION: sTREM-1 seems to behave as a novel mediator in IBD in correlation with the degree of the inflammatory reaction of the intestinal mucosa. AIM: To investigate the probable role of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in the pathogenesis of inflammatory bowel disease (IBD). METHODS: Fifty-eight patients were enrolled; nineteen healthy volunteers served as controls; 8 Patients were diagnosed with Crohn’s disease, and 31 with ulcerative colitis. Clinical and endoscopic activity indexes of patients with Crohn’s disease and ulcerative colitis respectively were estimated. by the thiobarbitourate assay, after passage through an HPLC system. RESULTS: Median ± SE of TNFα of controls, patients with Crohn’s disease and patients with ulcerative colitis were 6.02 ± 3.94, 7.98 ± 5.08 (P = NS vs controls), and 8.45 ± 4.15 sTREM-1 were 53.31 ± 32.93, 735.10 ± 197.17 (P = 0.008 vs controls) and 435.82 ± 279.71 ng / L respectively (P = 0.018 vs. controls) 1 was positively correlated with Crohn’s disease activity index and clinical and endoscopic activity indexes of ulcerative colitis (P = 0.002, 0.001 and 0.009, respectively). STREM-1 of patients with ulcerative colitis was positively correlated with TNFa (P = 0.001). CONCLUSION : sTREM-1 seems to behave as a novel mediator in IBD in correlation with the degree of the inflammatory reaction of the intestinal mucosa.