The aim of this study was to compare findings from clinical examinations, MRI scans and arthroscopy in ACL injury of the knee in order to assess the diagnostic significance of both examination findings. This study was conducted to manage the reliability of clinical diagnosis in ACL tear injuries. All patients attending our clinic with knee pain from 2009 to 2013 underwent systematic and thorough clinical assessment. Of 103 patients with knee problems arthroscopy ACL tears was diagnosed in 73. All these patients underwent therapeutic arthroscopic knee surgery. The clinical diagnosis was evaluated and confirmed during this procedure. The accuracy, sensitivity and specificity were calculated based on these arthroscopic findings. The MRI accuracy of clinical diagnosis in our study was 82.5% for ACL tears. Accuracy for two of three clinical examination tests of clinical diagnosis in our study was 96% and 94% for ACL tears. According to our obtained correlation between clinical examinations, MRI scan and arthroscopy for ACL injuries, we concluded that carefully performed clinical examination can give equal or better diagnosis of ACL injuries in comparison with MRI scan. Our study revealed MRI scan high sensitivity and specificity and not so high accuracy for ACL injuries of the knee joint in comparison with arthroscopy. MRI is an appropriate screening tool for therapeutic arthroscopy, making diagnostic arthroscopy unnecessary in most patients. According to our findings we can conclude that a positive anterior drawer test and a positive Lachman clinical examination test is more accurate for predicting, i.e. diagnosis of ACL tear. On the ither hand, MRI scan findings showed less accuracy for predicting, i.e. diagnosis of ACL tear. According to many studies of clinical examination tests compared (correlated) with arthroscopy, the accuracy of predicting ACL tears depends on the level of the skilled orthopaedic or trauma surgeon's hands. Based on these findings, we feel that MRI, except in certain circumstances, is an expensive and unnecessary diagnostic test in patients with suspected meniscal and ACL pathology.