Initially, we defined the posterior border of the level II, III, and IV nodes as a transverse line drawn through the posterior border of the sternocleidomastoid muscle on each axial scan. Any node lying posterior to this line would be considered to be a level V node. However, this led to a problem regarding the classification of the lowest jugular nodes, which, as Rouviere noted, were located on the anterior scalene muscle and which therefore were often referred to as the prescalene nodes.2,21 In many people, the posterior border of the sternocleidomastoid muscle lies anterior to the anterior scalene muscle on axial scans of the lower neck area. In such cases, if the posterior border of the sternocleidomastoid muscle were to be used as the division between the lowest level IV and V nodes, it would result in these scalene nodes being classified as level V nodes. Such classification would be contrary to the classic classification of the scalene nodes as being part of the internal jugular chain. Therefore, to separate level IV and level V nodes caudal to the bottom of the cricoid arch, we decided to use an oblique line extending from the posterior border of the sternocleidomastoid muscle to the lateral posterior edge of the anterior scalene muscle. Such a line would always place the scalene nodes in the internal jugular chain. The nodal classification that results from using these new landmarks is completely consistent with the recent AJCC classification and virtually all previous clinically based classifications.