The aim of our study was to assess the clinical significance of -174G/C Il-6 gene polymorphism and Il-6 serum level in patients with pancreatic adenocarcinoma (PA) and chronic pancreatitis (CP). The study included 41 with pancreatic adenocarcinoma, 56 with chronic pancreatitis, and 50 healthy volunteers, hospitalized between 2003 and 2006. Il-6 serum levels were measured with an enzyme-linked immunoassay and Il-6 gene polymorphism was studied in DNA isolated from peripheral blood. In PA and CP patients Il-6 serum levels were significantly higher than in the control group (P < 0.01). The levels of Il-6 in the patients with tumor size >or=3.5 cm were higher than that in patients with smaller tumors (P < 0.01). The elevated Il-6 levels were also correlated with the presence of liver metastases (P < 0.01). Mean Il-6 serum level was significantly higher in patients homozygous G/G for -174 Il-6 gene compared with patients with at least one C allele. Our findings indicate that -174G/C Il-6 gene polymorphism influences circulating Il-6 levels. Increased Il-6 serum levels may be correlated with tumor size and the presence of liver metastases in patients with pancreatic adenocarcinoma.