Sports participation is a major ally for the promotion of physical activity. However, sports injuries are important adverse effects of sports participation and should be monitored in sports populations. The purpose of this paper is to review the basic concepts of injury monitoring and discuss the implementation of these concepts in practice. The aspects discussed are: (1) sports injury definition; (2) classification of sports injuries; (3) population at risk, prevalence, and incidence; (4) severity measures; (5) economic costs; (6) systems developed to monitor sports injuries; and (7) online technology. Only with reliable monitoring systems applied in a continuous and long-term manner will it be possible to identify the burden of injuries, to identify the possible cases at an early stage, to implement early interventions, and to generate data for sports injury prevention. The implementation of sports injuries monitoring systems in practice is strongly recommended.