The purpose of the present study was to investigate the anterior type partial rotator cuff tear in throwing injuries of the shoulder. Thirty-three shoulders, who underwent arthroscopic surgery due to a throwing injury and in whom a rotator cuff tear was recognized, were investigated. First, they were divided into 2 groups according to the cite of the tear: the anterior type in 13, in which the tear was located at the anterior part of the suprasupinatus tendon, and the posterior type in 20, in which the tear was located around the border between the suprasupinatus and the infraspinatus tendon. Then, the patient's profiles, range of motion and joint laxity under general anesthesia, and the operative findings were compared between the 2 groups. As a result,10 of 13anterior type rotator cuff tears were restricted at the anterior 1/3 part of the supraspinatus tendon, and concealed type tears, in which an intratendinous degenerative tear was observed after a residual articular-side capsular portion was debrided, were recognized in 5. Posterior joint tightness at 90-degrees abducted position on examination under general anesthesia was recognized in 13 (100%) in the anterior type and in 13 (65%) in the posterior type, and posterior capsular tightness at arthroscopy was recognized in 11 (85%) in the anterior type and in 10 (50%)in the posterior type. Moreover, the greater tuberosity notch was recognized in 3 (23%)and 18(90%), respectively, and those factors showed a statistically significant difference. In conclusion, as the concealed type tear seen at the anterior part of the supraspinatus tendon was a representative lesion in an anterior type rotator cuff tear, the mechanism of an anterior type rotator cuff tear was suggested to be different from the posterior type. Posterior capsular tightness significantly related to the existence of anterior type rotator cuff tear. The presence of the greater tuberosity notch was seldom seen in the anterior type tear.