Using ultrasonography, we diagnosed rotator cuff tears in the dominant shoulder in 41 (47%) of the 87 players, while 4 players (5%) had rotator cuff tears in the nondominant shoulder. All tears were articular-sided partialthickness tears. In the dominant shoulder, 19 tears were in the supraspinatus tendon only, 13 in the infraspinatus tendon only, and 9 in both the supraspinatus and infraspinatus tendons. The tear depth (mean 6 SD) was 4.6 mm in the supraspinatus tendon and 6.2 6 3.6 mm in the infraspinatus tendon.