UNLABELLED: Posttreatment surveillance for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination, CT, and MRI. Several studies have shown that 18F-FDG PET may be an effective technique for the detection of persistent, recurrent, and distant metastatic HNSCC after treatment. The aim of this prospective study was to determine the benefits of hybrid 18F-FDG PET/CT in detecting a subclinical locoregional recurrence of HNSCC and distant metastases. The study patients were considered cured of HNSCC on the basis of 12 mo of negative findings on conventional follow-up. We also assessed the diagnostic accuracy of 18F-FDG PET/CT in these patients. METHODS: Ninety-one patients cured of HNSCC without any clinical evidence of recurrence were included. Whole-body 18F-FDG PET/CT examination was performed 11.6+/-4.4 mo after the end of the treatment. The gold standard was histopathology or 6 mo of imaging follow-up. RESULTS: The whole-body 18F-FDG PET/CT examinations had negative results in 52 patients and positive results in 39. Nine of these patients who exhibited abnormal 18F-FDG uptake in the head and neck area did not have recurrent HNSCC (false-positive). Thirty had proven recurrence. The sensitivity and specificity of 18F-FDG PET/CT in this study for the diagnosis of HNSCC recurrence were 100% (30/30) and 85% (52/61), respectively. The positive predictive value was 77% (30/39). The negative predictive value was 100% (52/52). The overall accuracy was 90% (82/91). CONCLUSION: The results of our study confirm the high effectiveness of 18F-FDG PET/CT in the assessment of HNSCC recurrence and suggest that 18F-FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC and could be proposed systematically at 12 mo of the usual follow-up.