Forty-eight patients with shoulder pain and 15 normal volunteers underwent rotator cuff imaging using high resolution real time ultrasound. The potential diagnostic value of sonography in detecting rotator cuff tears was evaluated by correlating ultrasound findings with surgical findings in 19 patients, 12 of whom also underwent preoperative arthrography. The preoperative ultrasound diagnosis was correct in 18 of the 19 patients undergoing surgery for possible rotator cuff tears. In the group of 12 surgical patients undergoing both preoperative arthrography and sonography, ultrasound correctly predicted the presence of a rotator cuff tear in 12 of 12 patients, while arthrography predicted cuff tears in only nine of 12. Good anatomic definition of the rotator cuff was obtained in both symptomatic and asymptomatic groups. The characteristic appearance of the normal and pathologic rotator cuff is described. Rotator cuff sonography promises to be a valuable new diagnostic tool for evaluating patients with suspected rotator cuff tears.