YKL-40 has been introduced as a marker of inflammation in different clinical situations. The association between YKL-40 and inflammation in chronic renal failure patients has not been researched currently. The objectives of this study were to establish serum YKL-40 concentrations in dialysis patients with chronic renal failure compared to healthy subjects and to explore its relationships with a proinflammatory cytokine, interleukine-6 (IL-6) and an acute phase mediator, high sensitivity C-reactive protein (hs-CRP). The study population included hemodialysis patients (N=43; mean age of 40.9 +/- 14.5), peritoneal dialysis patients (N=38; mean age of 45.8 +/- 13.7) and healthy subjects (N=37; mean age of 45.5 +/- 10.6). Serum concentrations of YKL-40, IL-6, hs-CRP and routine laboratory measures were evaluated. Compared to the healthy subjects, hemodialysis and peritoneal dialysis patients had higher concentrations of YKL-40, IL-6, hs-CRP, as well as lower concentrations of hemoglobin, serum albumin and high density lipoprotein-cholesterol (P<0.001). YKL-40 concentrations were positively correlated with serum creatinine (P<0.001, r=0.495), IL-6 (P<0.001, r=0.306), hs-CRP (P=0.001, r=0.306) levels and inversely correlated with hemoglobin (P=0.002, r=0.285), serum albumin (P<0.001, r=0.355) and high density lipoprotein-cholesterol (P=0.001, r=0.306). In multivariate regression analysis YKL-40 was associated with creatinine, serum albumin and hs-CRP concentrations after adjustments with covariates. Dialysis patients with chronic renal failure have elevated serum YKL-40 concentrations. Associations with standard inflammatory parameters suggest that YKL-40 might be a novel inflammatory marker in this population.