Methodology: All patients accrued to this study will have a series of pre-treatment evaluations, including history, physical, KPS evaluation, CT/MRI of the head and neck, chest x-ray or CT, dental examination, QOL assessment using the University of Washington QOL H&N symptom questionnaire (Hassan et al, 1993), and pre-treatment salivary flow measurements. All salivary flow measurements collected for this study will include unstimulated (resting) and stimulated (using citric acid solution), with a 5-minute collection time for each. Accrued patients will belong to one of two cohorts, which will determine the radiotherapy target volumes and dose levels: Group 1 - Patients who are treated with definitive radiotherapy (or chemoradiotherapy). The high dose region (PTV66) will consist of all areas of gross disease plus appropriate planning margin. The lower dose region (PTV54) will include PTV66 and all at-risk draining lymphatics of the neck. Group 2 - Patients treated with surgery and post-operative radiotherapy. The high-dose region (PTV60) will consist of the areas of previous gross disease and regions of the neck with metastatic lymph node involvement. The low-dose region (PTV54) will include PTV60 plus the remainder of the surgical bed and any additional regional lymphatic tissue considered to be at risk of harboring occult disease. All patients will be treated in 30 treatments (1 treatment per day, 5 days per week, for 6 weeks). PTV66 will receive 66 Gy, PTV54 will receive 54 Gy, etc. Thus different target regions will receive different doses per day (ranging from 1.8 to 2.2). In theory, giving high-risk regions a higher dose per day (hypofractionation) allows tumour cells less time to repopulate and should improve control rates (Fowler, 2000).