Abstract Background: Shoulder pain is one of the commonest musculoskeletal complaints presented to orthopedics and rheumatologists. Shoulder is a joint commonly affected by degenerative changes, overuse and traumatic lesions. Aim of Study: The purpose of this study is to evaluate the role of dynamic high resolution ultrasonography in the detec-tion of rotator cuff muscle injury, to find out the value added by dynamic ultrasonography to the static examination of such cases and to evaluate the value added by dynamic ultrasonogra-phoy to the management of the disease. This is compared to MRI which we considered as a standard to our cases. Material and Methods: This prospective study included 35 patients who were referred to the Radiology Department with clinically suspected rotator cuff injury. After detailed clinical examination, US examination of the involved shoulder was performed together with an examination of the contralat-eral normal shoulder, followed by MRI of the symptomatic shoulder in all 35 patients. The MRI findings were considered as final. Sensitivity and specificity for ultrasound in rotator cuff injuries was calculated with correlation with MRI. Results: In the present study, the majority of patients were in age group 18-57 years. A total of 35 patients were diagnosed as having rotator cuff muscle abnormality on US and MRI. In the diagnosis of rotator cuff muscle tear, the strength of agreement between US and MRI was good. Conclusion: Ultrasound of the shoulder show promising results in diagnosis of rotator cuff muscle injury and acromi-oclavicular join pathology. A wide viability, cost effectiveness and better tolerability of US make it amodality of first choice for evaluation in rotator cuff muscle pathology.