As shoulder arthroscopy is becoming increasingly widelyused, more emphasis should be placed on anatomic structures at risk to minimize the complications. Although the advances obtained in imaging techniques in parallel to the advancing technology provide substantial advantages to the shoulder arthroscopy, the neurovascular structures located between the skin and the glenohumeral joint or the subacromial space to which the tip of the portal is directed during the emplacement of the portals are at risk as the surgeon does not have a direct vision of these structures. The surgeons should have comprehensive knowledge of both the normal nerve anatomy of the shoulder and various nerve variations that may be present. Anterior portals, especially the 5-o`clock portals were reported to confer the highest risk for neurovascular injuries, especially also for the injuries of axillary nerve and artery and cephalic vein due to its close proximity to these structures. In addition to the neurovascular structures, surgeons should also have a thorough knowledge about the anatomy of the glenoid labrum and the relation between the neighboring muscles and tendons to recognize the lesions encountered during shoulder arthroscopy.