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 histolog -ical differentiation ,as well as depth of invasion ,clinical stage and lymph node metastasis .Results Her-2 am-plification 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 asso-ciated 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 .