Objective:To investigate the SIRT1 expressions in gastric cancer tissue and the potential association with clinicopathological characteristics and prognosis of the patients. Methods:The clinicopathological and survival information of the 142 cases who underwent radical gastrectomy at Nantong Cancer Hospital from January 1990 to December 1995,was collected to establish a combined database. The tissue microarray was made from the paraffin embed gastric cancer tissues and corresponding adjacent nontumoral gastric tissues from 142 resectable patients. Expressions of SIRT1 were evaluated by a semi-quantitative immunoreactivity scoring (IRS) procedure. The correlations between the expressions of the SIRT1 and clinicopathological as well as survival characteristics of patients were further analyzed. Results:Expressions of SIRT1 were significantly lower in cancer lesions than in adjacent noncancerous tissues. Low tumoral SIRT1 expression was associated with depth of invasion,presence of lymph node metastasis,high pTNM stage and poor differentiation,respectively. Importantly,reduced SIRT1 expressions in cancerous tissues were significantly correlated with shorter overall survival(OS) in patients (HR = 0.205,95%CI:0.124~0.339,P < 0.001). Conclusion:SIRT1 might be a novel biomarker for evaluating progression and prognosis of resectable gastric cancer patients.