Introduction.-Middle school children involved in sports sections are the most exposed to fatigue syndrome (or overtraining syndrome). This syndrome can be explored through an auto questionnaire of fatigue (Questionnaire de Fatigue de l'Enfant Sportif [QFES]). Moreover, the epidemiological studies about sports injuries in all ages reveal a peak in 13-14 years old children. Goal.-To determine the influence of the QFES score on the incidence of sports injuries in middle school athletes. Methods.-Two hundred and seventy-six children aged 11 to 16 years old involved in fifteen middle school sports sections, practicing an average of 10h48 +/- 3h30 min per week in eleven different sports were enrolled. From December 1st 2014 to April 15th 2015, each pupil completed a QFES and an injury questionnaire based on the 2006 and 2007 consensus statement of the International Federation of Football Association (FIFA) and the International Rugby board (IRB). Results.-Subjects who were injured in the previous two months had a higher QFES mean score compared to non-injured (36.5 +/- 19.6 vs. 25.7 +/- 14.1, P< 0.001). The rate of injuries increased with the QFES score (P < 0.01). The QFES score increased with body mass index (BMI) percentiles (y=0.0999x+25.166; r=0.176; P<0.01). Conclusion.-The QFES could be an effective tool to monitor and prevent the fatigue syndrome in middle school athletes. Sufficient rest periods in training plans and weight management could prevent children fatigue and sports injuries. (C) 2016 Elsevier Masson SAS. All rights reserved.