ABSTRACT: Numerous studies have detailed the physical health benefits of children's participation in sport and a growing body of research also highlights the benefits for mental health. Children who participate in sport have also been shown to be advantaged academically. However, despite the benefits there is evidence that children are leading increasingly sedentary lifestyles and are at greater risk of chronic disease than those with active lifestyles. Sport provides an important means for children to achieve their recommended amount of daily physical activity. This systematic review asks 'what are those barriers to children's participation in sport?'Literature searches were carried out in June 2015 using; EMBASE, Medline, CINAHL and SportDiscus using the search terms barrier*, stop*, prevent*, participat*, taking part, Sports/, sport*, "physical education", PE, child*, young person*, adolescen*. These were supplemented with hand searches. A total of 3434 records were identified of which 22 were suitable for inclusion in the review, two additional studies were identified from Google Scholar in November 2016. Both qualitative and quantitative studies were included. Study's included in the review assessed children up to 18 years of age. Study quality was assessed using Critical Appraisal Skills Programme (CASP) tools.Studies took place in the school environment (n = 14), sports club (n = 1), community setting (n = 8) and adolescent care setting (n = 1). Frequently reported barriers across quantitative studies were 'time' (n = 4), 'cost' (n = 3), 'opportunity/accessibility' (n = 3) and 'friends' (n = 2). Frequently reported barriers across qualitative studies were 'time' (n = 6), 'cost' (n = 5), 'not being good at sport' (n = 6) and 'fear of being judged/embarrassed' (n = 6).Policy makers, parents and teachers should all be aware that 'cost' and 'time' are key barriers to participation in sport. More local sports opportunities are needed where costs are reduced. Schools and local clubs could better work together to provide more affordable local opportunities to increase children's participation in sport.