Background/Aims: The aim of present study is to evaluate the predictive and prognostic role of high [18F]fluoro-D-glucose (FDG) uptake of primary tumor and nodal metastasis in squamous cell carcinoma of head and neck (HNSCC). Methodology and Patients: Between February 2006 and July 2010, we retrospectively evaluated 64 patients with primary HNSCC in an institutional imaging trial. All patients who underwent evaluation pretreatment FDG-positron emission tomography/computarized tomography (FDG-PET/CT) imaging and 33 (51%) had pre-and after treatment FDG-PET/CT imaging. All treatments were performed with curative intent. Abnormal FDG uptakes were analyzed using maximum standardized uptake values (SUVm). The disease-free survival (DFS) and overall survival (OS) were evaluated with several prognostic factors such as pre-treatment SUVm and % change in SUVm. Results: Tumor sites are nasopharynx (n=29, 45.3%), larynx (n=16, 25%), oropharynx (n=13, 20.4%) and hypopharynx (n=6, 9.4%). Median age was 58 (range: 16-87) and most patients (84.4%) had stage III/IV lesions. Objective response rate was 78.2 %. The median primary tumor SUVm was 13.4 (range, 4.8-33.1), median nodal SUVm was 4.45 (range, 0-25.6) and median % change in SUVm was 74.1(range, -61-100). On multivariate analysis, nodal SUVm and surgery remained significant predictors of DFS. There was no statistical significance found between survival and other factors. Conclusions: We have found that while nodal SUVm is prognostic for DFS, primary tumor SUVm and % change in SUVm are not.