Delineation of target volumes is increasingly recognized as the most crucial step within the process of modern conformal radiotherapy. In the field of head and neck radiation oncology, the need for a standardized methodology in the delineation of nodal regions of the neck on computed tomography (CT) images has recently emerged. To address this issue, a consensus document has been prepared by the Head and Neck Working Party of the AIRO-Lombardia Cooperative Group, based on the proceedings of multidisciplinary meetings and on literature findings. The document contains detailed guidelines for the delineation on CT images of the nodal regions of the neck, including for each nodal region (1 to 7) the description of anatomical limits as seen on CT images.