A 25-year-old woman presented with a fever, headache, vomiting and somnolence. Cranial magnetic resonance imaging (MRI) showed multiple lesions in the cerebellum, brainstem, cerebral cortex and subcortex. Oligoclonal bands were positive in the cerebral spinal fluid (CSF). She experienced a good recovery after steroid treatment. Four months later, she developed right vision loss. Repeated MRI showed multiple cranial lesions different from those involved in the first attack in both size and distribution. An abnormal high signal was also observed in the front and intraorbital regions of the right optic nerve. The patient's vision progressively improved, and she obtained a full recovery following the administration of steroids. A diagnosis of multiphasic disseminated encephalomyelitis manifesting with optic neuritis was made.