Abstract： Objective To investigate the high mobility group box chromosomal protein-1 (HMGB1) levels in patients with acute pancreatitis (AP); and to study the relationship between the serum level of HMGB1 and the severity of AP. Methods The patients' serum HMGB1 concentrations were determined right after admission, 24, 48 hour after admission. The levels of HMGB1 were measured by ELASA kit and its relationship with the severity of AP was analyzed. 20 healthy adults were treated as the control group. Results At the time of admission, and 24, 48 hours after admission, the serum HMGB1 levels in AP patients were (8.05 + 1.60 ), ( 8.04 ± 1.39 ), ( 8.25 ± 1.56) ng/ml, respectively, which were significantly higher than that in the healthy control [ ( 2.20 + 0.57 ) ng/ml, P ＜ 0. 01]. There were 35 patients with severe acute pancreatitis (SAP) and 27 patients with mild acute pancreatitis (MAP). The HMBG1 levels in patients with SAP were (7.99 + 1.69) ,(8.12 ± 1.40), (8.13 ± 1.34) ng/ml, and they were (8.12 + 1.52), (7.92 +1.40), (8.39 ± 1.81 )ng/ml in patients with MAP, and the difference between the two groups was not statistically significant. Conclusions The serum HMGB1 level in AP patients was significantly higher than that in healthy controls, but it was not related with the severity of AP.