Clinicians have been describing individuals with chronic fatigue states for over 100 years, although chronic fatigue syndrome is often regarded as a modern disease. The aetiology of chronic fatigue syndrome is uncertain. For young individuals with chronic fatigue syndrome there are neither reliable prevalence figures nor scientific evidence concerning the effectiveness of treatments. Information obtained from research into adult individuals with chronic fatigue syndrome may be helpful but is not necessarily directly applicable to children and adolescents. Developmental factors and the influence of other family members on the course of the disorder in young sufferers should be considered. The uncertainties surrounding chronic fatigue syndrome should not deter child and adolescent mental health workers from becoming involved in the assessment and management of individual patients. The mainstay of treatment is rehabilitation with an emphasis on gradually increasing activities. Considerable attention will need to be given to engaging the young people and their families and working effectively with a multidisciplinary team. If mental health workers do not become involved in treating young people with chronic fatigue syndrome there is a risk that psychological factors will not be addressed and that chronic functional impairment will ensue.