The aim of this study was to evaluate the change of supraspinatus muscle and tendon as well as biceps tendon after pitching in Korean professional baseball league pitchers by the application of sonoelastography. A total of 10 pitchers from Korean professional league were evaluated their supraspinatus muscle and tendon and long head of biceps tendon of dominant arm by sonoelastography at all-star break period. After one month later, re-evaluations were performed after pitching in the game. The strain ratio of supraspinatus muscle and tendon (red portion, soft; blue portion, hard), thickness of supraspinatus and long head of biceps tendons were evaluated. For the correlation analysis with pitching, numbers of pitches, maximal velocity, maximal difference of velocity and ratio of breaking balls among pitches were investigated. The strain ratios of supraspinatus muscle, thickness of supraspinatus and long head of biceps tendon were decreased but not statistically significant. However, the strain ratio of red portion in supraspinatus tendon was significantly increased. There were no correlations between sonoelastograpic findings and pitches.