Abstract: OBJECTIVE To explore the clinical significance of DJ-1 protein high expression in infected patients with pancreatic neuroendocrine tumor. METHODS 60 patients with PNENs admitted to our hospital from Jun. 2010 to Oct. 2013 were selected as subjects, and divided into the infected group (n=35) and the PNENs group (n=25). In the same period, 30 healthy people were enrolled in the control group. The ELISA method was used to detect serum DJ-1 protein levels in each group. The immunohistochemical staining method was used to examine the DJ-1 protein staining in excised tissue of PNENs patients in the infected group and the PNENs group. The relationship between clinicopathological parameters such as infection and DJ-1 protein expression in PNENs tissues was determined. In a follow-up period to Dec. 2016, the survival data of PNENs patients were collected and the effects of DJ-1 protein expression on OS and DFS were analyzed. RESULTS The serum DJ-1 protein levels in the PNENs group and infected group were significantly higher than those in the control group (P<0.001). The levels of DJ-1 protein in serum of patients with combined infection were significantly higher than those in PNENs group (P<0.001). The positive rate of DJ-1 protein in the infected group was higher than that of the PNENs group, but the difference was not statistically significant. DJ-1 protein expression was related to lymph node metastasis, distant metastasis, TNM staging and pathological grading. In patients with lymph node metastasis, distant metastasis, TNM stage of Ⅲ-Ⅳ, and high pathologic stage, the DJ-1 protein expression levels in PNENs tissues were relatively high. The univariate COX regression analysis results showed that the expression levels of DJ-1 protein in PNENs tissues were significantly correlated with OS (RR=6.845, 95% CI=1.560-30.221, P=0.013) and DFS (RR=2.565, 95% CI=1.141-5.884, P=0.025) of the PNENs patients. CONCLUSION Expression of DJ-1 protein is high in both serum and tissues of PNENs patients, and a higher level of DJ-1 protein is detected in patients combined with infection. DJ-1 protein expression is closely related to tumor invasion, metastasis, disease progression and prognosis.