PURPOSE: The anterior instability is representing approximately 95% of all shoulder instabilities that mainly caused by an abduction, extension, and external rotation of the shoulder movement. However capsular laxity and unstable glenohumeral joint which make the most frequently dislocated joint in shoulder have closely related with rotator cuff weakness. This study examines the association between strength and functional indices in patients with Bankart repair. The purpose of the study is the relationship between internal rotator and external rotator muscle strength, shoulder functional indices (ROWE and ASES scores) post one year of the Bankart repair. METHODS: This was a cross sectional study comprising of 40 patients, all males (24.5±13.5 yrs, ht 169.3±8.5 kg, and wt 67.8±11.4 kg) with Bankart lesion who may be treated arthroscopically. Isokinetic internal rotator(IR) and external rotator(ER) strength were evaluated with a CSMI dynamometer, with the subject seated and the shoulder abducted 45 in the scapular plane. Tests were performed at 60 /sec concentric mode for both sides. Shoulder strength was analyzed by comparison between involved side strength deficit and uninvolved side (side-to-side differences). Preoperatively and postoperatively, all the ROWE and ASES(American Shoulder and Elbow Surgeons) score was recorded that included subscores for ROM, muscle strength, pain, motion, and function.by the same exercise physiologist. RESULTS: The patients were divided into 4 groups for comparison in muscle strength deficit- Q1 (less than 20% difference in muscle strength deficit), Q2 (21-35% deficit), Q3 (36-50% deficit), and Q4 (more than 50% difference in muscle strength deficit). In our study, ROWE and ASES score (r = - .305; r = - .382) were significantly correlative difference in Q1 (less than 20% deficit) group with IR and ER muscle strength. CONCLUSIONS: This study suggests that muscle strength of the shoulder after Bankart repair will affect the functional ability more than any other factor. The muscle strength deficits in shoulder joint have significant negative consequences for the long term functional outcome after Bankart lesion. Therefore, it is deemed necessary to measure the muscle strength of the rotator cuff and continue rehabilitation exercise needed for recovery of muscle strength.