Carbohydrate antigen (CA) 19-9 is the only diagnostic marker used in pancreatic cancer despite its limitations. Here, we aimed to identify the diagnostic role of CEMIP (also called KIAA1199) combined with CA 19-9 in patients with pancreatic cancer. A retrospective analysis of prospectively collected patient samples was performed to determine the benefit of diagnostic markers in the diagnosis of pancreatic cancer. We investigated CEMIP and CA 19-9 levels in 324 patients with pancreatic cancer and 49 normal controls using serum enzyme-linked immunosorbent assay. Median CA 19-9 and CEMIP levels were 410.5 U/ml (40.8-3342.5) and 0.67 ng/ml (0.40-1.08), respectively, in patients with pancreatic cancer. The AUROC for CA 19-9 and CEMIP were 0.847 (95% confidence interval [CI]: 0.806-0.888) and 0.760 (95% CI: 0.689-0.831), respectively. Combination of CA 19-9 with CEMIP showed markedly improved AUROC over CA 19-9 alone in pancreatic cancer diagnosis (0.94 vs. 0.89; P < 0.0001). CEMIP showed a diagnostic yield of 86.1% (68/79) in CA 19-9 negative pancreatic cancer. Combined use with CEMIP showed significantly improved diagnostic value compared with CA 19-9 alone in pancreatic cancer. Especially, CEMIP may be a complementary marker in pancreatic cancer patients with normal CA 19-9 levels.