Background: The injury of the anterior cruciate ligament (ACL) is a common injury of the knee which needs an accurate medical management for avoidance of the complications. However, knowledge about the risk factors and effects of ACL are limited in Kingdom of Saudi Arabia (KSA). Objectives: Assessing the knowledge of Saudi subjects about the effects of anterior cruciate ligament (ACL) injury on daily activities in Al Ahsaa City, Kingdom of Saudi Arabia (KSA).        Methods:  A cross sectional study that included 700 Saudi subjects who were randomly chosen from June –August 2017. The volunteers were interviewed in shopping malls and filled out a questionnaire sheet that included information about their demographics and questions associated with ACL risk factors and outcomes. Results: About 6% of subjects declared suffering from ACL injuries.  The knowledge of respondents toward ACL injury definition, risk factors, symptoms, treatment and complications were inadequate among 71.3% of subjects.The good knowledge was significantly associated with the older age and male gender while the education level showed no association with knowledge score.  Conclusion: There was a lack of knowledge about ACL injuries among Saudi participants that need efficient educational campaigns for increasing the awareness about the etiology, risk factors, treatment and complications of ACL injuries.