Background and Aim: Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumor necrosis factor super family of structurally-related cytokines. The aim of this study was to determine the diagnostic and prognostic role of serum TWEAK concentration in patients with acute pancreatitis. Methods; Twenty four patients with acute pancreatitis and 24 consecutive healthy age- and sex-matched control subjects were included in the study. The serum concentrations of TWEAK were measured at admission and then at remission. The average time between admission and remission was 7-10 days. Results: At admission, TWEAK concentration was significantly lower in patients with acute pancreatitis compared to control subjects (p < 0.001). Serum TWEAK concentrations were elevated after the remission period, however the differences were not statistically significant. In addition, serum TWEAK concentration showed a significant, inverse correlation with amylase, lipase, CRP, AST, fibrinogen, LDH and a positive correlation with calcium, albumin and platelet count. Conclusions: Patients with acute pancreatitis have lower serum TWEAK concentration than healthy subjects. These results suggest that serum TWEAK concentration could be a potential biomarker of acute pancreatitis. © 2012 Informa Healthcare.