High-resolution real-time sonography has been reported as a non-invasive means of evaluating the integrity of the rotator cuff. Fifty-two patients underwent both sonographic and arthroscopic evaluation of the rotator cuff. There were 42 men and 10 women with an average age of 47 years (range 28-71 years). The duration of shoulder pain averaged 24 months (range 3 months to 9 years). Thirty-five rotator cuff tears were noted arthroscopically. Twenty-seven of the tears were diagnosed by sonography for a sensitivity rate of 77%. Eleven of the 17 intact rotator cuffs were normal by sonography for a specificity rate 65%. The overall accuracy of sonography was 73% and the predictive value of a positive sonogram was 82%. Sonography appears to be a good initial screening examination in evaluating the integrity of the rotator cuff. It is noninvasive and relatively inexpensive. Technical limitations of this technique as well as the experience of the radiologist in performing and interpreting the examination play a major role in the accuracy of this test. As instrumentation improves and as experience in using this technique increases, we expect the accuracy of sonography in detecting tears of the rotator cuff to continue to improve.