PET/CT has revolutionized the evaluation of patients with head and neck cancer by allowing more accurate staging, more focused treatment modalities, earlier detection of recurrent disease, and identification of incurable disease. In some clinical scenarios, PET/CT is clearly useful, while in others the cost may not be warranted. In this chapter, the authors review the literature on the use of PET/CT in head and neck cancers (in particular squamous cell carcinoma) and provide an evidence-based approach to the use of PET/CT for staging, treatment planning, monitoring of treatment response, and surveillance of treated patients with squamous cell carcinoma. They also briefly address the use of PET/CT for thyroid cancer, lymphoma, and melanoma. At the end of each section, key points are summarized in a box for quick reference.