Multiple sclerosis is a chronic, debilitating disease. Almost one in ten patients with MS has a history of disease onset during childhood. Although numerous therapeutic options exist for adult MS, the available treatments for pediatric patients are still limited. One of the emerging therapies is rituximab, a monoclonal anti-CD20 chimeric antibody that can deplete the CD20+ lymphocyte populations. A 12-year-old boy presented with ataxia, paresthesias, and headache while his brain MRI showed numerous T2 contrast-enhancing lesions. Gamma globulin, steroids, and cyclophosphamide failed to intercept his disease, and he progressed to a rapid clinical and radiological deterioration. Treatment with rituximab reversed the disease course in a dramatic fashion, leading to complete remission.