With a prevalence of about 2% obsessive-compulsive disorder is ranking among the most frequent psychiatric disorders in childhood and adolescence. The symptoms often lead to severe impairments in academic and social life, as well as to family conflicts. Despite the high efficacy of cognitive-behavioural and psychopharmacological interventions, the long-term course of the disorder is less favourable in a significant number of patients. A profound knowledge of the disorder is crucial to implement effective treatment strategies shortly after the onset of symptoms. This paper gives a review on juvenile obsessive-compulsive disorder and addresses issues of classification, epidemiology, symptoms, co-morbidity, diagnostics, aetiology, treatment strategies and the course of the disorder.