The aim of this study was to investigate the expression and prognostic significance of RIN1 in gastric adenocarcinoma. RIN1 expression was analyzed using quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemical staining on tissue samples from a consecutive series of 315 gastric adenocarcinoma patients who underwent tumor resections between 2003 and 2006. The relationship between RIN1 expression, clinicopathological factors, and patient survival was investigated. qRT-PCR results showed that the RIN1 mRNA expression was higher in tumor tissue samples than in the adjacent normal tissues, and a corresponding increase in protein expression was confirmed by Western blotting. Immunohistochemical staining indicated that RIN1 is highly expressed in 54.3 % of gastric adenocarcinomas. RIN1 expression levels were closely associated with tumor size, histological differentiation, tumor stage, and lymph node involvement. Kaplan-Meier survival analysis showed that high RIN1 expression exhibited a significant correlation with poor prognosis for gastric adenocarcinoma patients. Multivariate analysis revealed that RIN1 expression is an independent prognostic parameter for the overall survival rate of gastric adenocarcinoma patients. Our data suggest that RIN1 plays an important role in gastric adenocarcinoma progression and that a high RIN1 expression predicts an unfavorable prognosis in gastric adenocarcinoma patients.