A case of Graves' disease with white matter abnormalities is presented here. The diagnosis as Graves' disease was made when the patient was 5 years old, and a subtotal thyroidectomy was performed when she was 10. Her neurological symptoms began at age 19 with paresthesia of her legs and lower body. Cranial magnetic resonance imaging was normal; thoracic magnetic resonance imaging revealed demyelinating lesions. Intravenous pulse steroid therapy improved her symptoms. Ten months later she described dizziness, lower body paresthesia, and ataxia. Both her cranial and thoracic magnetic resonance imagings revealed demyelinating lesions. After pulse steroid therapy, glatiramer acetate therapy was initiated with diagnosis of an autoimmune multiphasic demyelinating syndrome. Five months later, she presented with right-sided mild optic neuritis followed by rapid spontaneous remission. Antithyroglobulin antibody levels remained normal; antithyroid peroxidase antibody level was high. This presents a rare case of Graves' disease associated with multiphasic demyelinating autoimmune syndrome.