Background: Multiple Sclerosis is the commonest immune mediated inflammatory disorder of the central nervous system. It is usually relapsing remitting and presents with focal neurological deficit. On the other hand ADEM (Acute Disseminated Encephalomyelitis) also known as postinfectous encephalomyelitis is a rare CNS demyelinating disorder which is typically monophisic and presents with encephalopathy. Objective: We would like to report a rare case of MS that present with ADEM like clinical and radiological picture. Material and Methods: A 16 year female presented to the emergency room with progressive deterioration in consciousness over five days. Results and conclusion: MRI Brain and Cervical spine was suggestive of ADEM while CSF examination and brain biopsy was suggestive of MS.