PET and PET/CT are the procedures of choice for molecular imaging in the head and neck area. The current data of the literature show, that functional imaging with fluorine-18-deoxyglucose ((18)F-FDG) provides the possibility to obtain information about the viability of malignant lesions. The use of hybrid systems, PET/CT, enables physicians to assess both, morphology and function, and achieve a high diagnostic accuracy exceeding 90%. PET with (18)F-FDG is the most sensitive method to detect tumor recurrence. However, false positive results must be considered due to unspecific changes following treatment, especially radiotherapy. The use of quantitative PET scans as well as the application of a second tracer, enhance the capability of PET to assess questionable masses more accurately. Follow up examinations with PET and (18)F-FDG provide data about early changes in the tumor metabolism due to chemotherapeutic treatment. Studies in patients undergoing surgery and radiotherapy demonstrated, that PET with (18)F-FDG can be used for the prediction of individual survival.