BACKGROUND: Shoulder pathologies need accurate diagnosis for best management and treatment provided to patients. OBJECTIVE: Determine the diagnostic sensitivity, specificity and accuracy of shoulder ultrasonography (US). DESIGN: Retrospective, analytical. SETTING: Tertiary care center in Riyadh, Saudi Arabia. PATIENTS AND METHODS: We included all shoulder exams performed between January 2010 and December 2016 that met the inclusion criteria. Data was collected retrospectively from the a picture archiving and communication system and patient records. The patients were evaluated using US for the presence of rotator cuff tears and classified into intact, full-thickness tear, partial-thickness tear, tendinosis, subacromial/subdeltoid bursitis and acromioclavicular joint degenerative changes. The US findings were correlated with the shoulder MRI study findings. The time interval between the US examination and MRI ranged from 0 to 180 days (6 months). MAIN OUTCOME MEASURES: To compare the sensitivity, specificity and accuracy of shoulder US studies in the detection of rotator cuff pathologies in comparison to MRI findings. SAMPLE SIZE AND CHARACTERISTICS: 86 (60 females, 26 male), mean age 53.7 years (range, 19-85). RESULTS: The sensitivity, specificity and accuracy of US for the detection of full-thickness supraspinatus tears compared with those of MRI were 86%, 82% and 83%, respectively. The sensitivity, specificity and accuracy of US for the detection of partial-thickness supraspinatus tears compared with those of MRI were 38%, 70% and 58%, respectively. Overall PPV, NPV, sensitivity, specificity and accuracy of US for the detection of full-thickness tears compared with those of MRI were 35%, 97%, 78%, 83% and 83%, respectively. For partial-thickness tears, the overall PPV, NPV, sensitivity, specificity and accuracy of US compared with those of MRI were 51%, 60%, 51%, 60% and 56%, respectively. CONCLUSION: Overall, US has high sensitivity, specificity and accuracy for the detection of full-thickness tears compared with the detection of partial-thickness tears. LIMITATIONS: Small sample size and retrospective. CONFLICT OF INTEREST: None.