Purpose: We reviewed the bilateral anterior shoulder instability to evaluate the final outcomes and influencing factors that had effect on the final outcomes. Materials and Methods: Sixteen patients of the bilateral shoulder instability underwent the operative treatment and 15 patients could be followed up average 29 months. There were Bankart lesions in 28 cases and 46% retracted markedly onto the medial side of the glenoid neck. Capsular redundancy could be seen in 50%, but the generalized ligamentous laxity in only two patients. We performed open Bankart repair in 21 cases and arthroscopic repair in 9 cases. Inferior capsular shift was performed in 12 cases of 15 cases in patients who was shown the capular redundancy. Results: The average increment of the forward flexion was 4° postoperatively but the average decrement of the external rotation was 6° postoperatively. After the inferior capsular shift surgery, there were significantly the decrement in external rotation by 13° even though the forward flexion was at the same level comparing with preoperative motion. There were 13 cases(43%) in excellent result, 14 cases(47%) in good and 3 case(l0%) in poor. Rowe score improved from 53 to 87.3 postoperatively. Conclusion : Re-establishing a proper capsular tensioning in a bilateral anterior shoulder instability is critical to ultimate success because there was a redundant laxity in a half and majority of them had marked retraction of an anteroinferior glenohumeral ligament complex. Especially, it should be considered that an unexpected limitation of external rotation could be occurred in the inferior capsular shift surgery.