A 30-year-old woman with the histologic diagnosis of lymphoepithelioma of the thymus is reported on. Investigation of Epstein-Barr serology showed evidence of infection, and Southern blot analysis showed the presence of the viral genome in the tumor specimen. The patient achieved complete remission after treatment with combination chemotherapy, autologous bone marrow transplant, and radiotherapy. These findings suggest that lymphoepithelioma of the thymus may have a viral pathogenesis similar to that of nasopharyngeal carcinoma.