Human demyelinating disease, multiple sclerosis, is now though to be caused by autoreactive T cells against several antigens in central nervous system. In experimental allergic encephalomyelitis, animal model of the disease, successful treatment is reported using a monoclonal antibody to T-cell receptor (TCR) of encephalitogenic T cells. Analoging this model, researchers are now trying to intervene T cells suspected to elicit the disease. For this purpose, myelin basic protein, one of the candidate CNS antigens, reactive T cells and usage of TCR in those cells are extensively examined. Although no convincing result was obtained so far because of complexity of the disease and a genetic background of human beings, T cell intervention may be beneficial to some patients with this disease.