This paper delineates which lymph nodes should be dissected due to the high frequency of metastasis associated with different types of primarily lesions of the thoracic esophagus. In cancer involving the upper third of the esophagus (Iu), lymph flow was found to be primary from the superior mediastinal area to the cervical area; in that involving the middle third (Im), it was broadly distributed from the superior, middle, and inferior mediastinal region to the cervical and abdominal regions; and in that involving the lower third (Ei), it tended to extend from the inferior mediastinal region to the abdominal region, with single primary metastatic nodes also being noted in this area. The significance of the "top" nodes, namely, the nodes located along the right recurrent laryngeal nerve in the upper portion of the thorax, was also investigated, and it was confirmed that the prognosis for patients with metastases to both the top nodes and other nodes was unfavorable. An immunohistochemical study on mediastinal lymph flow using the anti-Su-Ps antibody demonstrated interactions between top nodes and cervical and/or thoracic nodes.