A 14-year-old girl with Epstein-Barr virus (EBV) infection developed exophthalmos and ocular muscle swelling. The EBV genome was detected in T lymphocytes taken from the submandibular gland, temporal muscle and cervical lymph nodes. A surface marker analysis of her peripheral blood demonstrated that CD45RO-positive T lymphocytes were strongly activated. Immunosuppressive treatment, including steroid and cyclophosphamide, was effective in improving the symptoms. Immunosuppressive therapy may be included as the choice of treatment for EBV infection.