The two major imaging modalities used for assessment of soft tissue injuries are ultrasound and MRI. Although ultrasound of the extremities is used only to a limited extent in the United States, it is widely used in many other countries for evaluation of extremity injuries. This article first considers the advantages and disadvantages of MRI and ultrasound. Understanding these differences will help the reader understand the role of ultrasound as compared with MRI in evaluating upper extremity injuries. The uses of ultrasound for evaluating sports medicine injuries in specific regions of the upper extremity are then reviewed. Where the data are available, the reported accuracy of ultrasound is compared with MRI for each type of injury.