Background: A rotator cuff tear is a tear of one or more of the tendons of the four rotator cuff muscles of the shoulder. The rotator cuff is a group of muscles that play an important role in function of the glenohumeral joint. Value of the clinical examination of a shoulder is often uncommonly exhibited; therefore, imaging modalities have valuable implications in the management of rotator cuff pathologies. Aim: the purpose of this study is to assess the diagnostic accuracy of MRI in diagnosis of rotator cuff tears. Materials and Methods: we examined 20 consecutive cases of shoulder arthroscopy, who had undergone preoperative investigation in the form of MRI. Comparing the accuracy of MRI for detection of full-thickness rotator cuff tears, using the operative findings as the ‘gold standard' was used. All the patients presented to Radiology Department referred from Orthopedic Outpatient Clinic, El-Demerdash University Hospital and Nassir Institution, from January 2017 to October 2017. Results: 16(80%) were males, 4(20%) were females, with age range from (27y) to (57y) (mean range 42y) complaining of symptoms and signs of shoulder pain which go more with RCT the overall accuracy of MRI in diagnosis of RCT, was 99%, while sensitivity and specificity was 99%,98.8) respectively, with P value less than 0.05. Conclusion: MRI is an accurate diagnostic imaging method for RCT specially for the FTT, and considered to be best cost-effective, non-invasive imaging method for screening of rotator cuff tears. In patients who underwent surgery, MRI yielded comparably high sensitivity for detecting full-thickness RCT.