This article reviews basic shoulder anatomy and biomechanics and discusses the impact these have on the etiology of shoulder injuries in sports. Four types of sport activities lead to shoulder injuries:muscle and tendon overuse, acute tears of the dynamic stabilizers,impingement and overuse injury. Most shoulder injuries initially are treated nonoperatively with rehabilitation. Rehabilitation protocols are successful in most patients. This article also discusses why postoperative rehabilitation is vital to the ultimate success of patients who require operative treatment.