The objective of this study is to determine the effect of oral ketamine on pain and allodynia associated with multiple sclerosis. A 60-year-old woman with multiple sclerosis was referred to our clinic because of severe pain and allodynia. Oral ketamine was started at a dose of 20 mg once a day and increased to twice a day. Oral ketamine was effective in the treatment of the pain and allodynia associated with multiple sclerosis.