Background: Meniscal root tears (MRTs) are defined as radial tears within 1 cm of the meniscus insertion, or avulsions at the insertion of the meniscus. This study aimed to assess accuracy and role of MRI in diagnosis of Posterior Medial Meniscus Root Tear in comparison with arthroscopic findings. Methods: This cross-sectional observational study included 30 patients with suspected posterior root tear of medial meniscus who was admitted to Benha University Hospital. All patients were subjected to complete history taking, local examination and special tests as McMurray test, Radiological assessment including MRI Technique and Arthroscopic assessment. Results: Arthroscopic intervention with partial menisectomy was done for 2 cases of type1 injury and meniscial repair was done for 22 patients of all other types. So, we founded one False positive and one False negative case. According to Validity of MRI in diagnosis of PMMRT, MRI showed 96.15% Sensitivity, 75.00% Specificity and 77.12% Accuracy in diagnosis of PMMRT. Conclusion: MRI is a valid non-invasive technique in diagnosis of PMMRT and useful in detecting and classifying PMMRT which is helpful for orthopedic surgeons to manage PMMRL tears in clinical practice.