An assessment has been made regarding the lymph node dissection performed on 286 cases of right colon cancer undergoing operation at Cancer Institute Hospital from 1946 to 1989. As a result, it was reconfirmed that almost satisfactory result is obtainable by the existing standard mode of dissection on right colon cancers. However, there are cases in which prolonged prognosis is obtained by adding dissection along the right gastroepiploic artery such as subpylolic nodes, from which it is considered that dissection of the these lesions should be made with the same carefulness as that on the main nodes, particularly, in the so-called surgical trunk along the superior mesenteric vein. Hemicolectomy of the region including the ileocaecum is not necessarily required for the cancer present in the vicinity of the hepatic flexure. And, for the metastasis in the lymph nodes more than 3rd group, no influence is exerted on the prolonged prognosis only by explanation of the range for lymph node dissection.