Adenocarcinomas of the esophagogastric junction form a heterogeneous group of tumors. We aimed to evaluate the value of the expression pattern of cytokeratins 7, 19, and 20 for their diagnosis and classification. A total of 85 cases of adenocarcinoma of the distal esophagus and 67 cases of adenocarcinoma of the proximal stomach, defined on strict topographical criteria, were investigated. About 90% of the adenocarcinomas of distal esophagus were positive for cytokeratins 7 and 19, in contrast to <45% of the adenocarcinomas of proximal stomach (p <0.01); 17.6% of the adenocarcinomas of the distal esophagus and 55.2% of the adenocarcinomas of the proximal stomach expressed cytokeratin 20 (p <0.01); and 74.1% of the adenocarcinomas of the distal esophagus and 23.8% of the adenocarcinomas of the proximal stomach had a CK7+/CK20- immunophenotype (p <0.01). In intestinal-type tumors a CK7+/CK20- immunophenotype had a sensitivity of 76.5%, a specificity of 84.5%, and a predictive positive value of 87.3% for the diagnosis of adenocarcinoma of the distal esophagus. Cytokeratin patterns are different in adenocarcinomas of the distal esophagus and in adenocarcinomas of the proximal stomach. A CK7+/CK20- pattern is highly suggestive of an esophageal origin and may be helpful for the correct classification of esophagogastric adenocarcinomas.