A 15-year-old boy diagnosed with a severe, active, and aggressive form of multiple sclerosis (MS) failed conventional, evidence-based therapy. The optimal treatment of the child or adolescent failing federally approved therapy for MS is unclear, similar to the situation in adults. This case history demonstrates that aggressive immunosuppression might be of at least short-term value in controlling disease acutely in an adolescent, as in adults with MS, when evidence-based therapies do not provide an adequate response.