Background: Tumor invasion and metastasis are complex processes, involving regulation at the molecular level of adhesive molecules, proteolitic enzymes, and cell growth and angiogenesis factors. A Disintegrin and Metalloproteinase (ADAM)17 has been indicated to be indispensable regulator of celular event from proliferation to migration.Although prognostic importance of ADAM17 expression has been investigated in several tumors, its clinical utility as a useful prognostic molecular marker remains unclearin gastric cancer.In the present study, we evaluated the expression of ADAM17 and its prognostic significance in gastric cancer patients after surgery. Methods: Prognostic significance of ADAM17 expression was analyzed by immunohistochemically in 158 patients with gastric cancer and the relationship between its expression and clinicopathological factors was also evaluated. Results: High expression of ADAM17 was detected in 81 patients(51%),while low expression was found in 77 cases (49%). There was significant correlation between gender, histology, lymph node metastasis, vascular invasion, the presence of recurrence and high ADAM17 expression. Recurrence in patients with high ADAM17 expression was significantly higher than that for patients with low ADAM17 expression(p=0.032). The median disease-free survival (DFS) time for patients with high ADAM17 expressed tumors were worse than those of patients with low ADAM17 expressed tumor (16.6 vs. 44.2 months, p=0.004).In addition, patients with low ADAM17 expression had a higher median overall survival (OS)interval than those of high ADAM17 expressed patients (49.6 vs. 26.9 months, p=0.019). Multivariate analysis indicated that the rate of ADAM17 expression was an independent prognostic factor for DFS, in addition to known important clinicopathological prognostic indicator for DFS. But its' prognostic importance could not be proved by multivariate analysis for OS. Conclusions: The potential value of ADAM17 expression as a useful molecular marker in gastric cancer progression should be evaluated comprehensively,it may predict recurrence and poor prognosis in patients with gastric cancer after curative resection.