Posterior capsular tightness with glenohumeral internal rotation deficit is usually considered to be an acquired condition of the throwing shoulder and is usually treated conservatively. However, because posterior capsular tightness is sometimes irreversible, we have performed arthroscopic capsular release for painful throwing shoulder with posterior capsular tightness. The true loss of internal rotation and posterior stiffness was confirmed by examination with the patient under anesthesia, and contracture of the posterior capsule and the posterior band of the inferior glenohumeral ligamant was observed arthroscopically. Because an extensive adhesion between the capsule and the fascia of the external rotators was noted, a capsular release was performed from 6 o'clock to 11 o'clock (in the right shoulder) to completely expose the muscle belly of the external rotators. Of the first 16 consecutive patients, 4 had no concomitant lesions and underwent posterior capsular release alone. With a minimum of 2 years' follow-up, it was ascertained that the throwing pain completely disappeared in 14 patients and improved in 2. In all, 11 patients returned to their preinjury performance level, and 5 returned to a lower level of function. In the 4 patients who had no concomitant lesions, throwing pain completely disappeared, and all were able to return to their preinjury performance level.