Objective: To investigate the expression of Krüppel-like transcription factor 9 (KLF9) in pancreatic cancer tissue and its association with clinicopathologic features and prognosis of pancreatic cancer patients. Methods: The specimens of 200 paired pancreatic cancer and adjacent pancreatic tissues were collected. The KLF9 expressions in these specimens were determined by RT-PCR (28 pairs), Western blot (4 pairs), and immunohistochemical staining (all specimens), respectively, and the relations of KLF9 expressions with clinicopathologic features and postoperative survival of the patients were also analyzed. Results: The results of RT-PCR showed that the KLF9 mRNA expression level in pancreatic cancer tissue was remarkably lower than that in its adjacent pancreatic tissue in 21 of 28 paired specimens (75%). The results of Western blot showed that the KLF9 protein expression was obviously down-regulated in pancreatic cancer tissue compared with its adjacent pancreatic tissue. The results of immunohistochemical staining showed the KLF9 expression intensity was remarkably weaker in pancreatic cancer tissue than that in adjacent pancreatic tissue. The results of analyses of the relationship between KLF9 expression and clinicopathologic variables showed that the KLF9 expression level was significantly related to degree of tumor differentiation (P=0.008) and vascular invasion (P=0.006). Survival analysis showed that the 1-, 2- and 3-year overall survival rate in patients with positive KLF9 expression was significant higher than that in patients with negative KLF9 expression (41%, 31%, 16% vs. 18%, 6%, 6%), and the median survival time in patients with positive KLF9 expression was significant longer than that in patients with negative KLF9 expression (21.05 months vs. 11.82 months) (all P<0.05). Conclusion: KLF9 expression is decreased in pancreatic cancer, which is closely related to malignant unfavorable prognosis.