Abstract: Objective To investigate the expressions and clinical significances of aldehyde dehydrogenase 1（ALDH1） and Twist in gastric adenocarcinoma. Methods A total of 86 cases of gastric adenocarcinoma was included in this study. GAC specimens and normal gastric tissues were obtained from the patients. in situ hybridization method was used to detect the expression of ALDH1, Twist mRNA． Immuohistochemistry was used to detect the expression of ALDH1, Twist, E-cadherin and N-cadherin. The relationship of ALDH1 and Twist with epithelial-mesenchymal transition phenomenon was studied. Survival analysis was carried to demonstrate the relationships of clinical pathological parameters with 5-year survival rate. Results The positive rates of ALDH1Twist mRNA in GAC tissues were 57.0% and 53.5%, while the positive rates of proteins were 60.5% and 58.1%, which were significantly higher than those in normal controls （P<0.05）. The expression of ALDH1 protein was significantly correlated with TNM stage and lymph node metastasis （P<0.05）.The expression of Twist protein was significantly correlated with distant metastasis, lymph node metastasis and invasion depth (P<0.05). The expressions of ALDH1 and Twist were significantly correlated with low expression of E-cadherin and high expression of N-cadherin（P<0.05）. Univartate analysis showed TNM stage, lymph node metastasis, distant metastasis and tumor size, the expression of ALDH1 and Twist related to 5-year survival rate (P<0.05).Conclusion The enhanced expression of ALDH1 and Twist in gastric adenocarcinoma may play a role in GAC invasion, metastasis and prognosis．