Narcolepsy is a central neurologic system disease. It begins early in life with disabling symptoms including excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucination and nocturnal sleep fragmentation. Patient with typical symptoms of narcolepsy is diagnosed by objective data from nocturnal polysomnography and multiple sleep latency tests. Narcolepsy is controlled with various medications. Nowadays, modafinil with favorable side effects profiles compared with traditional stimulant is mainly used. Gamma hydroxyl butyrate is effective in cataplexy. Cataplexy is also controlled with antidepressant such as Venlafaxine, SSRI, and TCA. As the knowledge of pathophysiology of narcolepsy expands, new treatment including immunological method, application of hypocretin and histamine systems have been tried.