Objective To study the change of serum diamine oxidase (DAO) level in patients with severely acute pancreatitis (SAP) in order to explore the role of DAO in assessing the severity of SAP and the magnitude of gastrointestinal dysfunction.Methods From January 2012 through December 2013,56 SAP patients with 33 male and 23 female and average age (45-± 14) years admitted within 3 days after onset were enrolled for this study.At admission,serum diamine oxidase (DAO) was detected,and APACHE Ⅱ score,computed tomography severity index (CTSI) score and Balthazar grading and gastrointestinal dysfunction score were calculated.And at the corresponding time,serum procalcitonin (PCT) was detected.The correlations between serum DAO level and 4 other markers were analyzed.Results The high level of serum DAO was found at admission in SAP patients correlating positively with serum PCT concentrations (r =0.516,P＜ 0.01),APACHE Ⅱ score (r =0.631,P＜ 0.01),CTIS score (r=0.640,P ＜ 0.01),and the degree of gastrointestinal dysfunction (r =0.730,P ＜ 0.01).Conclusions The role of serum DAO in assessing the severity of SAP and magnitude of gastrointestinal dysfunction in SAP patients is really valid.