We checked and analysed the clinical and radiological status of the upper extremities of 142 baseball player in childhood and adolescence. The results of this study were as follow:1. The oreder of frequency of pain locations in the upper extremities was elbow, shoulder, and then wrist joint. 2. There was colse relationship between elbow pain and career, but not in shoulder and wrist area. 3. The characteristics of shoulder or wrist pain were diffuse and vague nature, but elbow pain was located in medial aspect. 4. The cubitus valgus and limited elbow ROM in throwing side were found in pitchers or older careers. 5. All players showed cortiocotrabecular hypertrophy of humerus, and high incidence of medial epicondylar changes were noticed with career increased. 6. Main bony changes: Shoulder - widening of proximal humeral epiphysis. Elbow - hypertrophy of medial epicondyle. Wrist - hypertrophy of distal ulnar epiphysis. 7. Following radiological changes were noticed in upper extremities; Hypertrophy, Changes in epiphyseal plates, Fragmentation and avulsion fractures, Avasculsr changes.