During the last decades the prevalence of childhood and adolescent obesity in Europe has grown. Although it is possibly levelling off in some areas of Europe, the scale of childhood obesity and its associated morbidities and costs remains considerable. Obese children and adolescents are more likely than others to have risk factors for cardiovascular diseases, experience other health conditions associated with increased weight, such as type 2 diabetes and sleep apnoea, perform poorly at school and suffer psychological distress. Clear evidence for successful and cost-effective non-surgical strategies for treating childhood obesity is lacking, leading the medical profession to turn increasingly to surgical treatment options. While bariatric surgery is established as a safe and effective alternative with well-defined risks for severely obese adults, little of quality has been published on its use in children, with their unique metabolic, developmental and physiological needs. Evidence is needed on the effectiveness and cost–effectiveness of surgical treatment in order to support policymakers and guide future research.