BACKGROUND: Most data on sports injuries are gathered in clinical settings so that their epidemiology in the general population is not well known. OBJECTIVE: To explore the link between sports injuries with the type and the amount of sports activity and biological factors. METHODS: In 1996, 3,609 in-school adolescents 10-19 years (1,847 girls and 1,762 boys) participated in a regional survey. This included anthropometric measurements and a self administered questionnaire. RESULTS: Altogether 28.2% of girls and 35.9% of boys reported one or more sports injuries during the previous year and 2.1% of girls and 6.5% of boys reported at least one hospitalization due to a sports injury. Using the mean rate of injuries as reference level, some sports are highly related to injury occurrence: body building (relative risk (RR) 1.7, 95% confidence interval (CI) 1.5 to 1.9), skateboarding and rollerskating (RR 1.6, 1.4 to 1.8), athletics (RR 1.5, 1.3 to 1.7), snowboarding (RR 1.5, 1.4 to 1.6), basketball (RR 1.3, 1.2 to 1.4), soccer (RR 1.3, 1.2 to 1.4), and ice hockey (RR 1.2, 1.1 to 1.3). Using a logistic regression, several variables associated with a higher risk of injury were identified: the amount of physical activity, high risk sports, and Tanner pubertal stages. CONCLUSION: The risk of sports injury increases not so much with age but with exposure to specific sports and with pubertal development.