History taking, physical examination and x-ray study of both elbows were made on 55 senior high school, college and vocational baseball pitchers who visited the Department of Orthopedic Surgery of Hanyang University Hospital from March 1, 1980 to April 30, 1980. The results of this study were as follows: 1. Average age of 13 high school pitchers was 17.2 years, of 20 college pitchers was 20.1 years, and of 22 vocational pitchers was 23.4 years and average duration of pitching of high school pitchers was 3.8 years, college pitchers was 7.4 years, and vocational pitchers was 9.8 years. 2. Overhand type pitchers were 39(70.9%) and it was the most common pitching style. 3. 45(81.8%) complained elbow pain and the order of frequency was medial, lateral, and posterior. 4. 45(81.8%) showed hpertrophy of forearm and 38(69.1%) showed hypertrophy of arm. 5. Valgus deformity of the elbow joint was observed In 34(61.8%) and flexion contracture of the elbow joint was in 41 (74.5%). 6. Changes on x-ray were ossicle, traction spur, humeroulnar hypertrophy, narrowing of joint space, calciflcation of soft tissue and others. 7. Changes on x-ray were in proportion to duration of pitching and especially combined Iesions were observed more often ln overhand type pitchers.