99 patients with unilateral subacromial pain syndrome were randomized to perform a 10-week exercise therapy program on either the affected (Exercise group) or unaffected shoulder (Control group) after all patients were given steroid injections in the painful shoulder. The purpose of this study was to determine the effects of exercise therapy in addition to steroid injection with regards to shoulder pain during activity and at rest, clinical impingement signs, subacromial bursa size, self-reported shoulder function, and isometric muscle strength. Patients were followed-up at 13 and 26 weeks. The findings of this trial indicated that the addition of an exercise therapy program targeting the affected shoulder to steroid injections did not provide additional benefits when compared to patients who received only the steroid injections. There was, however, one exception with patients who received the additional exercise program having significantly fewer instances of impingement identified via ultrasound at week 13.