Abstract: Objective To study the protein expression and gene amplification of human epidermal growth factor receptor-2(Her-2)in adenocarcinoma of the gastroesophageal junction and its association with the clinicopathological features.Methods Immunohistochemical method and fluorescence in situ hybridization(FISH)were used to detect Her-2 expression and gene amplification in 80 surgically resected gastroesophageal junction cancer tissue.We further analyzed the relationship between the gastroesophageal junction cancer histological differentiation,as well as depth of invasion,clinical stage and lymph node metastasis.Results Her-2 amplification of gastroesophageal junction carcinoma by FISH was 22.5%,while the overexpression by IHC was 15%.Her-2 gene amplification and protein overexpression were correlated with the differentiation,clinical TNM stage,invasive depth and lymph node metastasis of the carcinoma(all P＜0.05).Her-2 expression was not associated with the patients age,gender,invasive depth and lymph node metastasis(P＜0.05).Conclusion Her-2 protein expression and gene amplification may be a prognostic indicator for the patients with gastroesophageal junction cancer.The joint detection of Her-2 protein expression level and the gene amplification can guide the prognosis and therapy for adenocarcinoma of the gastroesophageal junction.