Defective control of Epstein–Barr virus (EBV) infection by cytotoxic CD8⁺ T cells might predispose to multiple sclerosis (MS) by allowing EBV-infected autoreactive B cells to accumulate in the central nervous system. We have treated a patient with secondary progressive MS with in vitro-expanded autologous EBV-specific CD8⁺ T cells directed against viral latent proteins. This adoptive immunotherapy had no adverse effects and the patient showed clinical improvement with reduced disease activity on magnetic resonance imaging and decreased intrathecal immunoglobulin production. This is the first report of the use of EBV-specific adoptive immunotherapy to treat MS or any other autoimmune disease.