Rotator cuff tears account for almost 50% of major shoulder injuries but are sometimes difficult to diagnose. To aid diagnosis, we did a prospective study, comparing results of 23 clinical tests from 400 patients with and without rotator cuff tears. Three simple tests were predictive for rotator cuff tear: supraspinatus weakness, weakness in external rotation, and impingement. When all three were positive, or if two tests were positive and the patient was aged 60 or older, the individual had a 98% chance of having a rotator cuff tear; combined absence of these features excluded this diagnosis.