The main objective of this research is to identify risk factors for severe playground injuries among children aged 1 to 14 years who visited the emergency room of a paediatric hospital in Montreal, during the summer of 1991. Secondary objectives are to study determinants of the occurrence of playground injuries, to estimate injury rates adjusted for exposure, and to do recommendations for prevention. To document circumstances of each injury, telephone interviews were completed with parents of children and a response rate of 90% was obtained.The objectives of this research required different study designs. The principal objective was achieved through a case-control study. In this study, logistic regressions were performed to study risk factors of serious (AIS3, n = 88) and moderate injuries (AIS2, n = 203), using minor injuries (AIS1, n = 348) as the reference category. One of our secondary objectives was to analyze risk factors for injury occurrence. For this, two additional case-control studies were performed. In the first study, cases related to playgrounds (n = 639) were compared with control children who had visited the emergency room for another type of injury (n = 1064). In the second study, characteristics of playgrounds where an injury occurred were compared with playgrounds with no injuries. Finally, qualitative analyses were conducted to describe the scenarios of the injury incidents. To prevent future incidents, the Canadian Standards on Children's Playspaces and Equipment were reviewed to identify playground elements associated with injuries.As they become older, boys tend to sustain more severe injuries than girls. Children who use playgrounds less frequently are at lower risk of being injured, however, when they are injured, the injuries are more severe. Approximately 75% of all playground injuries resulted from a fall. Injuries from falls are more severe than other types of injuries. Public playgrounds account for 71% of injuries and home playgrounds for 21%. Injuries sustained at public playgrounds are more severe than injuries at home, except among children aged 1 to 4. The rate of injury is higher on modules (combination of several types of equipment including swings, climbers and slides) and swings than on slides and climbers. However, injuries on slides are more severe. The odds of serious injuries are 2.1 times greater for a fall on grass compared to one on sand (CI: 1.08; 3.96). The height of the equipment also appears to be a risk factor for incidence and severity of injury. For all hospitals in Montreal during 1991, the average rate of emergency room visits for playground injuries among children aged 1 to 14 years is 397 per 100,000 children for the period May to September. Injury rates are higher for children under 10 years old and among boys.In conclusion, the findings regarding playground surfaces are the most important, and suggest that, under equipment, grass should be replaced by sand. This recommendation applies to both public and home playgrounds. Prevention programs should focus on ensuring that playgrounds are in compliance with Canadian Safety Standards and should include both public and home playgrounds