Objective: To investigate the expression of transmembrane protease, serine 4 (TMPRSS4) and its clinical significance in gastric cancer. Methods: The mRNA and protein expressions of TMPRSS4 in 33 specimens of gastric cancer along with their adjacent tissues were measured by real-time RT-PCR and Western blot analysis, respectively. The TMPRSS4 expressions in 108 paraffin specimens of gastric cancer along with their adjacent tissues were determined by immunohistochemical staining, and the relations of TMPRSS4 expression with the clinicopathological profiles and prognosis of gastric cancer patients were analyzed. Results: Both the TMPRSS4 mRNA and protein levels in gastric cancer tissue were significantly higher than those in adjacent tissues (both P<0.05). TMPRSS4 expression rate in gastric cancer tissue was significantly higher than that in adjacent tissue (55.56% vs. 18.52%) (P<0.05), and high TMPRSS4 expression was significantly related to the tumor size (≥5 cm), depth of invasion, TNM stage and lymph node metastases (≥3) (all P<0.05). Kaplan-Meier survival analysis showed that the 5-year overall survival in TMPRSS4 expression patients was poorer than that in low TMPRSS4 expression patients (P=0.035). Cox analysis revealed that the high TMPRSS4 expression was an independent prognostic factor for gastric cancer patients (P=0.045). Conclusion: The TMPRSS4 level is closely associated with the progression of gastric cancer and could be used as a potential prognostic marker for gastric cancer.