For effective rehabilitation of the shoulder, physical therapists must have correct knowledge of shoulder movements. The purpose of this study was to determine the relationship between shoulder movements and the rotation of the humerus in the sagittal, coronal and scapular planes. Fifty normal subjects(25 male, 25 female) were tested using a Dualar-plus digital goniometer and an air-splint. The subjects performed active shoulder elevation in each plane with the humerus rotated in both medial and lateral directions. The range of motion(ROM) of the glenohumeral joint was measured three times. The paired t-test was used to determine the difference in ROM between medial and lateral rotation of the humerus. Results showed that, in the sagittal and the coronal planes, there was a significant difference(p < 0.01) in ROM of the shoulder between medial rotation and lateral rotation which was greater. But in the scapular plane, there was no difference between medial and lateral rotation. Physical therapists should consider these results when the goal of treatment is to increase ROM of the shoulder.