A 52-year-old woman, who had ischemic infarction in the ventral upper brainstem due to subarachnoid hemorrhage in October 1986, had recurrent sleep and cataplexy attacks from May 1987. She was receiving valproate and phenytoin daily since 1986. The diagnosis of narcolepsy was made based on the clinical symptoms and EEG findings showing REM sleep during a sleep attack. Both sleep and cataplexy attack increased in parallel with an increase of the dose of anti-convulsant drugs and disappeared immediately after the discontinuation of the treatment. The findings that suggest that the administration of anti-convulsant drug as well as the brainstem vascular lesion was deeply involved in the development of narcolepsy in this case.