The human epidermal growth factor receptor-2 gene (HER-2) encodes for a membrane-bound tyrosine kinase (Her-2), which is overexpressed in various human cancers. Her-2-targeted therapy has recently been shown to be beneficial for patients with advanced gastric cancer. Her-2 protein expression was investigated in 341 esophageal carcinomas [152 squamous cell carcinomas (SCC), 189 adenocarcinomas (AC)], 39 cases of Barrett mucosa, and 11 cases of squamous cell dysplasia. HER-2 gene amplification was assessed by colorimetric in-situ hybridization. Positive Her-2 status was found in 15.3% of ACs and 3.9% of SCCs. Positive Her-2-status was more common in dysplastic Barrett mucosas compared with nondysplastic ones (P=0.04). In 26% of the patients with ACs who had received neoadjuvant chemotherapy (n=39), the Her-2 status of pretherapeutic biopsies was different compared with subsequent surgical specimens. There was no statistically significant correlation between Her-2 status and patients' survival. Although Her-2 overexpression is rare in SCCs, it is found in 15.3% of ACs, where amplification of HER-2 gene and overexpression of Her-2 protein seem to be early events in carcinogenesis. The evaluation of Her-2 status in tumor biopsies and in particular in the context with possible alterations after neoadjuvant treatment can potentially lead to false Her-2-staging. Although Her-2-overexpression in esophageal cancer seems to have no influence on patients' survival, these subtypes of esophageal ACs have to be considered as targets for an anti-Her-2 therapy.