Background: Rupture of the anterior cruciate ligament (ACL) is a common cause of knee instability, requiring ACL reconstructions with about one million completed worldwide annually. Successful (ACL) reconstruction requires physical rehabilitation to help patients return to an active lifestyle. This study aimed toevaluate the effect of exercises program on knee functional outcomes for patients after arthroscopic anterior cruciate ligament reconstruction. Study design: Quasi experimental research design was conducted in this research. Study sample:Purposive sample of 60 adult patients of both sexes, who were diagnosed as a first-time primary unilateral anterior cruciate ligament injury and undergoing (ACL) reconstructionwere involved in the study and were divided randomly into two groups 30 patients for each group . Setting: The study was conducted at the knee arthroscopic surgery and stadium injuries unit at Mansoura University Hospital as well as the knee surgery outpatient clinic for patients follow up .Tools of the study: Five tools were utilized in this study: Tool I: Patient's assessment structure interview sheet which consists of two parts: Part (1): Socio-demographic characteristics and health relevant data, Part (2): The patient's knowledge and practice assessment sheet.Tool II: Manual muscle testing (MMT) Scale of the knee muscles. Tool III: Anterior Knee Pain Scale (AKPS) ― Kujala Scale‖. Tool (IV): Goniometric Range of Motion Measurement (ROM). Tool (V): The Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS).Results:The result revealed that post program implementation, study group had a reduction in pain and improvement in knee muscle strength and knee function more than the control group and a statistically significant improvement was found in the total mean score of (KOS-ADLS) of the patient in the study group (70.57 ± 3.87) compared to patient in the control group (40.86
± 3.37). Moreover the total mean score of knee flexion was significantly improved in the study group (109.0 ± 8.35) than the control group (77.0 ± 10.14). Furthermore the total score of knee extension was significantly better in study group in comparison with the control group. Conclusions:Exercises program after arthroscopic anterior cruciate ligament reconstruction had a significant positive effect on patient's knee functional outcomes.