We report a case of neuropsychiatric systemic lupus erythematosus successfully treated with mycophenolate mofetil (MMF). The patient was a 40-year-old female who maintained with 7 mg of prednisolone plus 100 mg of azathioprine (AZ) per day. According to transient ischemic attack that occurred repeatedly and an elevated level of interleukin-6 (IL-6) in spinal fluid, she was diagnosed as having neuropsychiatric systemic lupus erythematosus (NPSLE). Initial increase in doses of prednisolone and AZ to 20 mg and 150 mg per day, respectively, was ineffective. After switching from AZ to MMF, her symptoms of NPSLE completely resolved with marked improvement of the IL-6 level in her spinal fluid, suggesting that MMF was effective.