Objective:To investigate the expression of soluble T cell immunoglobulin and mucin domain-3 (Tim-3) in peripheral blood of patients with pancreatic cancer and its diagnostic value in combination with serum Carbohydrate antigen 19-9 (CA19-9) .Methods:106 newly diagnosed pancreatic cancer patients and 65 age and sex matched healthy individuals were enrolled. Tim-3 concentration was quantitatively determined by enzyme-linked immunosorbent assay (ELISA). According to the expression levels of soluble Tim-3 and serum CA19-9, a binary logistic regression model of receiver operating characteristic (ROC) curve was established to compare the diagnostic effects of serum CA19-9 and soluble Tim-3 alone or combined with the two tests.Results:The levels of soluble Tim-3 in the pancreatic cancer group were significantly higher than those in the healthy control group ( P<0.001). The expression level of soluble Tim-3 was significantly higher in patients with stage III-IV pancreatic cancer than in patients with stage I-II ( P=0.003). The AUC of soluble Tim-3 diagnosis for stage I-II pancreatic cancer was 0.856 (95%CI: 0.765 to 0.992 P<0.001), Serum CA19-9 The AUC used for the stage I-II pancreatic cancer diagnosis was 0.862 (95%CI: 0.772 to 0.926 P<0.001), The AUC for the combined diagnosis was 0.949 (95%CI: 0.880 - 0.985 P<0.001) ; In a healthy population and in patients with stage III-IV pancreatic cancer, the AUC of soluble T I I-IV pancreatic cancer in stage III was 0.927 (95%CI: 0.873 to 0.963 P<0.001), the AUC of serum CA19-9 used for the diagnosis of stage III-IV pancreatic cancer was 0.933 (95%CI: 0.881 to 0.968 P<0.001), the AUC for the combined diagnosis was 0.989 (95%CI: 0.956 to 0.999 P<0.001) . Conclusions:The combination of soluble Tim-3 and serum CA19-9 can improve the diagnostic rate of pancreatic cancer patients.