This article reviews the expected lymphatic drainage of various subsites of the upper aerodigestive tract and correlates this with the current nodal classification system. The surgical results of Lindberg and Byers et al correlate with the anatomic dissections of Rouvière and suggest that there are predictable pathways of lymphatic drainage within the subsites of the upper aerodigestive tract. These results form the basis of modified and selective neck dissections and radiation treatment planning. It should be emphasized that tumors attain the lymphatic drainage associated with their primary location. Tumors that cross the midline to the contralateral side or spread to adjacent subsites will acquire the lymphatic drainage associated within those areas. Clinicians who specialize in head and neck cancer have endorsed the imaging-based classification. The boundaries of the nodal levels are easily discernible by radiologists and yield consistent nodal classifications. The reproducibility of this classification makes this information important all physicians to participate in the care of patients with head and neck cancer.