The Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC). Serological studies have shown that the clinical onset of NPC is preceded by the appearance of a high antibody titer of IgA to viral capsid antigens and early antigens. The titers increase with the total tumor burden and the antibodies decline with the response to therapy. In patients with confirmed clinical remission elevation of IgA serological titers is highly significant for prediction of relapse. This demonstrates the usefulness of EBV serology for the clinical management of NPC patients.