Background: Concurrent chemoradiotherapy (CCRT) with or without adjuvant chemotherapy is the mainstay of treatment for locally advanced nasopharyngeal carcinoma (NPC). However the benefit of adjuvant chemotherapy has been controversial and search for adequate predictive factors is warranted. We conduct this study to evaluate the predictive values of mean standardized uptake value (SUV) measured in [(18)F]-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) for adjuvant chemotherapy in patients with locally advanced NPC. Methods: From January 2004 and July 2010, Data collection were performed in 108 NPC patients who underwent (18)F-FDG-PET before CCRT and adjuvant chemotherapy. The SUV was recorded for the primary tumor. All patients received intensity modulated radiotherapy. Concurrent chemotherapy was composed of cisplatin 100mg/m² triweekly. Adjuvant chemotherapy was consisted of 3 cycles of cisplatin 75 milligrams/m² and fluorouracil 1000 milligrams/m²for 4 days. Results: The median follow-up was 41months. The optimal cutoff value was 8.35 for SUV. 63.8% of patients had lower SUV (n=69), and 36.2% had higher SUV (n=39). Patients with a lower SUV had a significantly better 3-year overall survival (OS), disease-specific survival (DDS), and distant relapse-free survival (DRFS), but showed no difference in local relapse-free survival. Multivariate analysis showed only stage, SUV and adjuvant chemotherapy were significant in terms of overall survival. In patients with higher SUV, those receiving adjuvant chemotherapy had significantly higher 3-year OS, DDS, and DRFS compared with those without adjuvant chemotherapy. However, in those with lower SUV, there was no difference of OS, DDS and DRFS between patients with and without adjuvant chemotherapy. Conclusions: SUV of (18)F-FDG-PET for primary tumor could identify NPC patients who benefit from adjuvant chemotherapy.