In this study, NPC patients (stage III-IV A, except T3-4 N0 and T3 N1) who finished the curative radiotherapy will be randomized to the observation group and capecitabine group (650 mg/m2 bid, p.o.，d1-21，q3wks; continued until disease progression, unacceptable toxicity, or over 1 year). The primary endpoint is progression-free survival (PFS). Secondary end points include overall survival (OS), distant failure-free survival (D-FFS), locoregional failure-free survival (LR-FFS), toxic effects, and quality of life (QOL). All efficacy analyses are conducted in the intention-to-treat population, and the safety population include only patients who receive their randomly assigned treatment.