Rotator cuff tears and instability of the glenohumeral joint are a common cause of chronic shoulder pain and disability. Currently CT arthrography is the method of choice to evaluate the extent of osseous and soft tissue abnormalities. This study was undertaken to determine if magnetic resonance imaging was able to depict post-dislocation abnormalities and rotator cuff pathology and if MRI can replace CT arthrography. Sixty four patients, who were operated on for the first time (arthroscopy or arthrotomy) between November 1986 and July 1991, were compared in a blinded fashion with the results of MR imaging in 40 cases and of CT arthrographies in 24 cases. For the evaluation of rotator cuff tears MRI proved to have a sensitivity of 83.3% and an accuracy of 90.3%. Labral pathology was depicted with a sensitivity of 69.2% and an accuracy of 87.1%. In cases involving a Hill-Sachs lesion the sensitivity of MRI was 90% and the accuracy 95%. MR imaging is an accurate method in the evaluation of rotator cuff pathology and to some extent labral abnormalities.