Abstract: It is important to understand the biomechanical risk factors of the non-contact ACL injury to develop effective prevention programs.The purpose of this study was to validate a stochastic biomechanical model for non-contact ACL injuries, which can determine the causeand-effect relationship and risk factors.Methods:A stochastic biomechanical model for noncontact ACL injuries was developed and instrumented to a Monte Carlo simulation to estimate the ACL injury rate and risk factors during landing of the stop-jump task.The distributions of independent variables were determined from vivo data of 19 male and 18 female athletes.Results:The female-to-male non-contact ACL injury rate ratio was 4.91±0.25.In the simulated injured trials, there are smaller knee flexion angle, greater posterior GRF, and greater proximal tibia anterior shear force in comparison to the simulated uninjured trials.Conclusion:The estimated female-to-male non-contact ACL injury rate ratio and knee flexion angle for the injury were similar to that reported in the literature, which supports the overall validity of the model for estimating ACL loading.1st peak posterior ground reaction force and knee flexion angle are two important risk factors of non-contact ACL injury.