Objectives: Anxiety is more prevalent in children with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) than in the general population. A systematic review was carried out to identify which treatment methods are most effective for children with Chronic Fatigue Syndrome and anxiety. Design: Systematic review using search terms entered into the Cochrane library and OVID to search the databases MEDLINE, EMBASE and psychINFO.Participants: Studies were selected if participants were < 18 years old, diagnosed with CFS/ME (using CDC, NICE or Oxford criteria) and had a valid assessment of anxiety. Interventions: We included observational studies and Randomised Controlled Trials (RCTs). Comparison: Any or none. Outcomes: Change in anxiety diagnostic status and/or change in anxiety severity on a validated measure of anxiety from pre-treatment to post-treatment. Results: The review identified 9 papers from 8 studies that met the inclusion criteria. None of the studies specifically targeted anxiety but 6 studies tested an intervention and measured anxiety as a secondary outcome. Of these studies, 4 used a CBT-type approach to treat CFS/ME, one used a behavioural approach and one compared a drug treatment, gammaglobulin, to a placebo. Three of the CBT-type studies described an improvement in anxiety as did the trial of gammaglobulin. As none of the studies stratified outcomes according to anxiety diagnostic status or severity we were unable to determine whether anxiety changed prognosis or whether treatments were equally effective in those with co-morbid anxiety compared to those without. Conclusion: We do not know what treatment should be offered for children with both anxiety and CFS/ME. Further research is therefore required to answer this question.