The established and emerging roles of FDG positron-emission tomography/computed tomography (PET/CT) in the evaluation of squamous cell carcinoma of head and neck region is reviewed with a strong clinical focus on recommended applications and methodologies. In the staging of newly diagnosed disease, detection of cervical nodal involvement is the major indication but exclusion of distant metastases and of synchronous primary malignancy is also a valuable adjunct. Use in radiotherapy planning is advantageous for locally-advanced disease. Although there are few data yet to assess the use of FDG PET/CT to assess response during therapy, there is good evidence that this technique can accurately assess the post-treatment neck to identify those who might benefit from salvage therapy and those in whom observation or palliative treatment might be more appropriate. Although more expensive than other imaging modalities used for assessing this disease, the superior diagnostic accuracy and impact of incremental information provided by this technology has been shown to be cost-effective in several clinical scenarios.