This study aims to evaluate the impact of pretreatment thrombocytosis on survival in patients with nasopharyngeal carcinoma (NPC). The data of 1,582 patients with NPC, who underwent definitive treatment between 2003 and 2004, were retrospectively reviewed. The correlation between the clinicopathological variables and the platelet count was analyzed. The prognostic significance of thrombocytosis, together with various clinicopathological factors, was evaluated by univariate and multivariate analyses. Platelet count showed significant correlation with gender, clinical stage, and T stage in univariate analysis. There was poorer 5-year disease-specific survival (DSS) in the patients with thrombocytosis than in those without thrombocytosis (70 vs. 78 %; p = 0.001) and poorer metastases-free survival (MFS) (81 vs. 88 %; p = 0.006). Univariate and multivariate analyses showed that thrombocytosis was an independent prognostic factor for MFS and DSS. Thrombocytosis is a useful predictor of metastasis and poor prognosis in patients with NPC.