The increasing prevalence of obesity is not only observed in adults. Children are affected by obesity and related diseases, such as chronic liver disease, more frequently than in the past. Nonalcoholic fatty-liver disease is an important cause of chronic liver disease and in the near future will become important worldwide. Considering this phenomenon, it is important for gastroenterologists and hepatologists to be aware of the presence of nonalcoholic fatty-liver disease in pediatric populations and to treat it adequately. This practice will have important benefits for future generations. This review discusses the most important aspects in epidemiology, diagnostics and treatment of nonalcoholic fatty-liver disease in children.