[en] To explore the temporal profile of the peripheral neutrophil-to-lymphocyte ratio (NLR) in patients with locally advanced nasopharyngeal carcinoma (LANPC) and the potential prognostic value of its dynamic changes. Complete blood count of 112 patients from a previous phase II study were retrospectively collected at the timepoints of the initiation of induction chemotherapy (pre-IC), within 1 week before radiotherapy started (pre-RT), and within 1 week after radiotherapy finished (post-RT). Data of 103 patients were fully recorded and Cox regression analysis was used to analyze the correlations of potential risk factors with 5‑year overall survival (OS). The performance of the prognostic factor was validated in another independent cohort of 103 matched (by T and N stage) patients selected from 236 consecutive NPC patients treated with IC and concurrent chemoradiation. Multivariate analysis (MVA) identified patient age >50 years old (hazard ratio [HR] = 3.4, p = 0.02), weight loss during RT >7.5% (HR = 3.2, p = 0.03), and post-RT peripheral NLR >7.05 (vs. NLR ≤7.05, HR = 2.5, p = 0.04, 5‑year OS 71.4% vs. 87.8%) as unfavorable prognostic factors for OS. There was also a non-significant trend in the MVA that patients with post-RT peripheral NLR >7.05 showed worse progression-free survival (PFS; HR = 1.9, p = 0.06, 5‑year PFS 64.1% vs. 81.8%). Post-RT NLR had a good prognostic performance in the validation cohort (concordance index = 0.73, standard error 0.10; p = 0.02, Wilcoxon test). Post-RT NLR is an independent prognostic factor for OS in LANPC patients. The dynamic change of the routinely tested inflammatory variable could help selection of appropriate treatment options and follow-up strategies.