This chapter reviews the clinical and polysomnographic features of elderly narcoleptic subjects, and considers co-morbidity and therapeutic issues. A number of narcoleptic patients are older than 40 at diagnosis, this being due either to mild disease severity or misdiagnosis, or diagnosis delayed until late-life expression of cataplexy, or narcolepsy lacking cataplexy. Knowledge about the co-morbid disorders in narcolepsy is important inasmuch as it may sometimes contribute to diagnosis and it may also bring some insights into the pathophysiology of narcolepsy. Among the most frequently associated diseases were parasomnias, sleep-related breathing disorders, sleep-related movement disorders, internistic diseases, neurological disorders, and psychiatric disorders. Moreover, various drugs, such as stimulants, antidepressants, and sodium oxybate used in narcolepsy have been tested in adult patients over a range of ages, but not specifically in elderly subjects.