In 2003, a panel of experts published a set of consensus guidelines for the delineation of the neck node levels in node negative patients (Radiother Oncol, 69: 227-36, 2003). In 2006, these guidelines were extended to include the characteristics of the node positive and the post-operative neck (Radiother Oncol, 79: 15-20, 2006). These guidelines did not fully address all nodal regions and some of the anatomic descriptions were ambiguous, thereby limiting consistent use of the recommendations. In this framework, a task force comprising opinion leaders in the field of head and neck radiation oncology from European, Asian, Australia/New Zealand and North American clinical research organizations was formed to review and update the previously published guidelines on nodal level delineation. Based on the nomenclature proposed by the American Head and Neck Society and the American Academy of Otolaryngology-Head and Neck Surgery, and in alignment with the TNM atlas for lymph nodes in the neck, 10 node groups (some being divided into several levels) were defined with a concise description of their main anatomic boundaries, the normal structures juxtaposed to these nodes, and the main tumor sites at risk for harboring metastases in those levels. Emphasis was placed on those levels not adequately considered previously (or not addressed at all); these included the lower neck (e.g. supraclavicular nodes), the scalp (e.g. retroauricular and occipital nodes), and the face (e.g. buccal and parotid nodes). Lastly, peculiarities pertaining to the node-positive and the post-operative clinical scenarios were also discussed. In conclusion, implementation of these guidelines in the daily practice of radiation oncology should contribute to the reduction of treatment variations from clinician to clinician and facilitate the conduct of multi-institutional clinical trials.