Chronic fatigue syndrome is a debilitating condition that can lead to severe impairment of function. It places a considerable burden on the individual, their carers and society. No single cause has been found, and it is likely to be a condition of multiple aetiologies. Delays in diagnosis can lead to increased disability and less chance of successful treatment. Effective treatments are available in the form of cognitive behavioural therapy and graded exercise therapy, and both treatments have been recommended by the National Institute for Health and Care Excellence.