Based on Siewert classification, adenocarcinomas of the esophagogastric junction (AEGs) have different behaviors of perigastric-mediastinal nodal metastasis. Siewert type I AEGs have higher incidence of mediastinal nodal metastasis than those of type II or III, especially at middle-upper mediastinum. With regard to the necessity of mediastinal lymphadenectomy, theoretically, transthoracic esophagogastrectomy with complete mediastinal lymphadenectomy is suggested for Siewert type I AEGs, while transhiatal total gastrectomy with lower mediastinal and D2 perigastric lymphadenectomy is a standard surgery for type II-III AEGs. Nevertheless, the mediastinal nodal metastasis is an independent factor of poor prognosis for any type of AEG.