Aim of the study: Previous results from our trial showed that adjuvant cisplatin and fluorouracil chemotherapy did not significantly improve survival after concurrent chemoradiotherapy (CCRT) in locoregionally advanced nasopharyngeal carcinoma (NPC) at 2 years. Here, we present the data of long-term survival and late toxicities to further assess the ultimate therapeutic index of adjuvant chemotherapy (AC). Methods: Patients with stage III-IVB (except T3-4N0) NPC were randomly assigned to receive CCRT plus AC or CCRT only at seven institutions in China. Patients in both groups received cisplatin 40 mg/m(2) weekly up to 7 weeks concurrently with radiotherapy. The CCRT plus AC group subsequently received adjuvant cisplatin 80 mg/m(2) and fluorouracil 800 mg/m(2)/d for 120 h every 4 weeks for three cycles. The primary end-point was failure free survival. Results: Two hundred and fifty-one patients were randomised to the CCRT plus AC group and 257 to the CCRT only group. After a median follow-up of 68.4 months, estimated 5-year failure-free survival rate was 75% in the CCRT plus AC group and 71% in the CCRT only group (hazard ratio 0.88, 95% confidence interval 0.64-1.22; p = 0.45). 66 (27%) of 249 patients in the CCRT plus AC group and 53 (21%) of 254 patients in the CCRT only group developed one or more late grade 3-4 toxicities (p = 0.14). Conclusion: Adjuvant cisplatin and fluorouracil chemotherapy still failed to demonstrate significant survival benefit after CCRT in locoregionally advanced NPC based on the longterm follow-up data, and addition of adjuvant cisplatin and fluorouracil did not significantly increase late toxicities. Registration number: NCT00677118. (C) 2017 Elsevier Ltd. All rights reserved.