Narcolepsy is a socially and psychologically disabling disease that most often develops in adolescence or early adulthood. In a number of studies about one-third of the patients had experienced the first symptoms before the age of 15. The diagnosis and subsequent treatment is usually not established until several years later, often ten to fifteen years after the appearance of the first symptoms. If unrecognized and untreated, narcolepsy may lead to serious psychological and social problems during childhood and early adulthood, which may in turn cause difficulties in social adjustment later in life. This stresses the importance of early diagnosis. The diagnosis is based on clinical and polysomnographic criteria. In children, however, the clinical symptoms and polysomnographic findings may be atypical, making it difficult to establish a definite diagnosis. Three patients, two five-year olds and one four and a half-year old, are presented to illustrate the problems and considerations which must be taken into account in the diagnosis and treatment of children with narcolepsy.