Narcolepsy is a chronic disease commonly diagnosed in middle adulthood. However, the first symptoms often appear in childhood and/or adolescence. Pediatric cases of narcolepsy are among the most often underrecognised and underdiagnosed diseases. This fact raises questions about the reasons for such diagnostic delay from the clinical point of view, and what kind of help can be expected from auxiliary diagnostic examinations. The aim of the review is to stress some specific features of the clinical picture in children, to discuss the role of auxiliary examinations at the onset of the disease including sleep studies, tests for human leukocyte antigens (HLAs), and cerebrospinal fluid hypocretin (Hcrt) measurement, and to draw attention to the most common cases of pediatric misdiagnosis. Frequent cataplectic attacks at an early age should lead to detailed clinical, neuroimaging and genetic examinations to rule out a secondary etiology. Beside the typical symptoms (excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic/hypnopompic hallucinations), some additional features including obesity and nocturnal bulimia can appear. Also poor school performance and emotional disorder are common complaints. Treatment should start as early as possible to avoid the development of problems with progress at school, and close cooperation between school and family should be maintained.