For more than a decade, positron emission tomography (PET) has had an important role in the management of thyroid cancer patients. It may be involved in initial, sometimes inadvertent, diagnosis; in postoperative evaluation; in detection of occult metastases; in the evaluation of thyroid nodules; and in prognostication of metastatic disease. In this review we will update the advances in the application of PET scanning to optimal patient management. The majority of the published studies to date have used 18F-fluoro-deoxyglucose (FDG) as the PET isotope, and unless specifically noted, all references to PET scanning will imply that this tracer has been used.