We retrospectively reviewed 19 patients (19 shoulders) in whom advanced glenohumeral arthritis developed after anterior instability repair. The anterior instability repairs included 4 Bristow, 4 Putti-Platt (2 in combination with other procedures), 4 Magnuson-Stack, 2 Bankart, and 5 other anterior capsulorrhaphies. Seventeen of the shoulders were treated with arthroplasty: 15 with total shoulder replacement and 2 with humeral head replacement, at a mean age of 45 years (range, 32-69 years). Two patients did not have surgical treatment. The mean internal rotation contracture was 58 degrees (15 degrees -125 degrees ). Eleven patients (65%) required subscapularis lengthening and anterior capsular release to correct a severe internal rotation contracture. Three (18%) had glenoid bone grafting, and one had glenoidplasty to correct severe posterior glenoid wear. The results were evaluated after a mean follow-up of 62 months (range, 24-167 months). Arthroplasty reduced the level of pain in 16 cases (94%). Active forward elevation increased 21 degrees to 120 degrees, active external rotation increased 38 degrees to 41 degrees, and passive internal rotation increased a mean of 3 vertebral levels to T12. There was improvement in functional use of the upper extremity in all cases except one. Subjectively, 12 shoulders were rated as much better, 4 as better, and 1 as worse than preoperatively. Three underwent revision arthroplasty procedures. Advanced glenohumeral arthritis is a rarely reported late sequela of anterior instability surgery. It is more common after nonanatomic repairs, presents in patients at younger ages than typical glenohumeral osteoarthritis, and is characterized by severe internal rotation contracture and posterior glenoid wear. Prosthetic arthroplasty, although technically challenging, effectively reduced pain and improved function in our series.