Background: The prevalence of overweight and obesity among Swedish school children aged 6 to 16 years has increased at the same time as the physical activity levels has decreased. To overcome overweight or obesity actions need to be taken to improve physical activity in Swedish school children. Aim: To describe the significance of physical activity for Swedish school children with overweight and obesity. Method: The study was carried out as a literature study where ten articles were reviewed. The results were summarized after that the most meaningful units had been collected. Then themes were created based on these units. Results: Physical activity has a number of different impacts for children with overweight and obesity. It affects the children’s sleeping habits, fitness, insulin concentrations, BMI and oxygen uptake. Conclusion: The conclusion from this study showed that the performance of physical activity has different effects on Swedish school children's physical health. Many of the effects have a positive influence on these children.