The concurrence of multiple sclerosis and primary intracranial neoplasm is uncommon. We reported a 15-year old girl known to have multiple sclerosis (MS), who later developed cerebral glioma. The tumor was documented on the brain magnetic resonance imaging during the work up for an apparent relapsing MS, and subsequently confirmed pathologically by stereotactic biopsy. Because no singleclinical feature or diagnostic test was sufficient for the diagnosis of MS, a combination of both clinical and paraclinical studies should be included. If clinical and paraclincal studies are atypical, additional studies, such as brain biopsy, may help differential diagnosis of other MS mimicking diseases. (J Korean Acad Rehab Med 2005; 29: 521-526)
