Impingement syndrome is mechanical impingement between the greater tubercle of the humerus and the under surface of the coracoacromial arch, is a common source of shoulder pain in the athletes as well as non-athletes. Several factors contribute to shoulder impingement syndrome, including rotator cuff weakness, capsular tightness, poor scapulohumeral rhythm, and muscle imbalance of the scapular upward rotation force couple. The purpose of this article is to review current concepts of anatomy and biomechanics and the underlying pathomechanics as it relates to evaluation and treatment of shoulder impingement syndrome.