Introduction: Due to a high prevalence of low back pain (LBP) among children and adolescents, it is significant to seek effective prevention and therapeutic procedures. One idea for the programmes is a potential relation between the occurrence of LBP and the level of physical activity. The aim of this review was to analyse the current knowledge regarding the association between physical activity and LBP among children and adolescents. Methods: Publications were retrieved by searching the following databases: PubMed, The Cochrane library, Web of Science, Medline and SportDiscus with Full Text (EBSCO). The search strategy included keywords related to physical activity and LBP. The studies included were assessed for methodological quality. PRISMA guidelines were followed for the systematic review. Results: The total sample size of the nine included studies consisted of 75,233 subjects, with an age range of 9-19 years. All the studies were assessed to be of high quality. One cohort study and five cross-sectional studies found the association between physical activity and LBP in children and adolescents. The remaining studies found no relationship between physical activity and LBP. These findings showed that both extremes of activity levels (i.e. being very low and very high physically active) are associated with LBP. Conclusion: There is moderate evidence for the association between physical activity and LBP in children and adolescents. The results highlight the need for continued research. It seems that for clear evaluation of the analysed association the prospective cohort studies should be conducted.