Background-Although such data are available for young competitive athletes, the prevalence, characteristics, and outcome of sports-related sudden death have not been assessed previously in the general population. Methods and Results-A prospective and comprehensive national survey was performed throughout France from 2005 to 2010, involving subjects 10 to 75 years of age. Case detection for sports-related sudden death, including resuscitated cardiac arrest, was undertaken via national ambulance service reporting and Web-based screening of media releases. The overall burden of sports-related sudden death was 4.6 cases per million population per year, with 6% of cases occurring in young competitive athletes. Sensitivity analyses used to address suspected underreporting demonstrated an incidence ranging from 5 to 17 new cases per million population per year. More than 90% of cases occurred in the context of recreational sports. The age of subjects was relatively young (meanϮSD 46Ϯ15 years), with a predominance of men (95%). Although most cases were witnessed (93%), bystander cardiopulmonary resuscitation was only commenced in 30.7% of cases. Bystander cardiopulmonary resuscitation (odds ratio 3.73, 95% confidence interval 2.19 to 6.39, PϽ0.0001) and initial use of cardiac defibrillation (odds ratio 3.71, 95% confidence interval 2.07 to 6.64, PϽ0.0001) were the strongest independent predictors for survival to hospital discharge (15.7%, 95% confidence interval 13.2% to 18.2%). Conclusions-Sports-related sudden death in the general population is considerably more common than previously suspected. Most cases are witnessed, yet bystander cardiopulmonary resuscitation was only initiated in one third of cases. Given the often predictable setting of sports-related sudden death and that prompt interventions were significantly associated with improved survival, these data have implications for health services planning. (Circulation. 2011;124: 672-681.)Key Words: arrhythmia Ⅲ cardiac arrest Ⅲ athletes Ⅲ cardiopulmonary resuscitation Ⅲ defibrillation Ⅲ bystander help Ⅲ exercise, physical A lthough regular physical activity benefits cardiovascular health, 1 sport, particularly when practiced vigorously, has been shown to increase the risk of dying suddenly during or shortly after exercise. 2,3 The devastating consequences of unexpected sports-related sudden death (SD) and the recent availability of public access defibrillation mandate a thorough understanding of this phenomenon across the general population. 4 -6 To date, the large majority of data regarding sports-related SD have focused on young competitive athletes, 7,8 whereas literature on sports-related SD during recreational sports activities in the community remains sparse. 9,10 No prospective evaluation of sports-related SD in the general population, including young competitive athletes, has been published to date. Clinical Perspective on p 681Sports-related SDs in young competitive athletes are highly visible and usually attract considerable public and media atten...