BackgroundOver recent years, more anterior cruciate ligament (ACL) ruptures in badminton players have occurred. Little is known about the injury mechanism in badminton. The hypothesis is that most ACL injuries occur with single leg landings on the non-dominant leg in the backhand side or with lunge movements in the forehand side on the dominant leg. To inform prevention strategies the aim of this study was to investigate the mechanism of ACL injuries in badminton, specifically if ACL injuries occur in certain positions on the badminton court and/or with certain movements. Secondary aims were to investigate differences among gender, age groups and between recreational and tournament players. MethodsThe study, ACL Denmark, investigate ACL ruptures in a cohort of 90.610 participants diagnosed between 2000 and 2018. Of those, 539 participants reported ACL rupture during badminton and filled in an online questionnaire in December 2021–January 2022 on the injury mechanism and other injury characteristics. Data is presented as numbers, percentage, means (SD) and median (IQR) with chi square test or Fischers exact test for dichotomous outcomes. ResultsMost participants played badminton (n = 435, 81 %) as primary sport and 155 (29 %) reported to play on a competitive level (Tegner score 8). The rear court (n = 285, 40 %) was the most frequent location of injury but with a high percentage on the front and midcourt (n = 154, 22 %). The rear court was more prevalent among players aged 18–29 (p < 0.001). The most prevalent movement preceding the ACL injury was the scissor kick jump on the rear court (100, 19 %) followed by lunge at the net (70, 13 %) and lunge at the rear court (69, 13 %). One hundred and six players (15 %) were injured preceded by a deceptive shot from the opponent. The dominant leg was mainly injured in the forehand side and the non-dominant leg mainly in the backhand side. ConclusionThe most prevalent movement preceding the ACL injury was the lunge followed by the scissor kick jump. The rear court was the primary location of ACL injury in badminton and the dominant knee has a higher risk of injury in the forehand side and the non-dominant knee in the backhand side. More focus on the technical performance of lunge and scissor kick jumps and development of a badminton specific ACL injury prevention program is needed in badminton.