Studies and surveys of sport-related musculoskeletal injuries vary in their methods of ascertaining epidemiological data. The definition of a sport-related injury generally includes such descriptions as time loss, decreased level of participation, need for medical attention, or athlete exposure. The risks and pattern of sport injuries is affected by different factors that include age, biologic maturity, gender, type of sport, athlete’s level of fitness, a history of previous injury, sports environment, training and conditioning, and level of competition. Strategies for prevention of musculoskeletal sport injuries are guided by an understanding of the epidemiology and risk factors for injuries. One widely applied prevention model identifies internal risk factors for injury that predisposes the athlete to an increased risk for injury. These include age (maturation, aging), sex, body composition, status of general health, status of overall physical health and fitness, any anatomical factors (such as alignment, intercondylar notch width), and skill level of the athlete for specific sport. The susceptibility of the athlete for an injury is increased when the athlete with one or more internal risk factors is exposed to external risk factors. External risk factors include human factors (such as teammates, opponents, and referee), individual protective equipment, sport equipment, and the environment under which the sport is played (such as weather, playing surface). This chapter provides an overview of epidemiology and prevention of sports-related musculoskeletal injuries; more specific data are provided in chapters on specific injuries.