Abstract： Objective To investigate the expression of TMPRSS4 mRNA,protein in human pancreatic cancer tissues and to explore the relationship between the expression of TMPRSS4 protein and the clinicopathologic parameters.Methods Real-time PCR and Western blotting were used to detect the expressions of TMPRSS4 mRNA and protein in 16 samples of pancreatic cancer tissues and adjacent normal pancreatic tissues.The expression of TMPRSS4 protein in 61 samples of pancreatic cancer tissues and 26 samples of adjacent pancreatic tissues and 4 samples of normal pancreatic tissues was detected by using immunohistochemistry and its relationship with clinicopathological features was analyzed.Results The expression of TMPRSS4 mRNA and protein of pancreatic cancer tissues were significantly higher than those in adjacent pancreatic tissues (9.09 ± 7.01 vs.1.27 ± 0.72; 1.223 ± 0.125 vs.0.667 ± 0.106,P ＜ 0.01 ) ;the expression rate of TMPRSS4 protein of pancreatic cancer tissues was 67.2％ (41/61),which were significantly higher than that in adjacent pancreatic tissues[3.8％ (1/26),P ＜ 0.01].There was no TMPRSS4 protein expression in normal pancreatic tissues.There was no significant correlation between the expression of TMPRSS4 protein and the age,gender,tumor location or tumor size was found.There was significant correlation between the expression of TMPRSS4 protein and the degree of differentiation,lymph node metastasis,and clinical staging (P ＜ 0.05 ).Conclusions TMPRSS4 protein is highly expressed in pancreatic cancer tissues,and the expression of TMPRSS4 is associated with the degree of malignancy of pancreatic cancer.