Os acromiale is the rare shoulder disease and its treatment is controversial. Despite conservative treat-ments for 6 months include medication, exercise, physical therapy and subacromial steroid injections,operative treatment for uncontrolled symptomatic Os acromiale is considered the treatment of choice.Operative treatment includes excision, arthroscopic or open reduction and internal fixation with a bonegraft. Open reduction with tension band wiring and a bone graft is now the preferred treatment.We experienced 8 patients with symptomatic Os acromiale from March, 2001 to March, 2006. The aver-age patient’s age was 45 years and the man and women ratio were 2: 6. All 8 cases of symptomatic Osacromiale of the mesoacromion were treated with open reduction and internal fixation using tension-bandwiring. The preoperative ASES(47.3 ±24.4) and UCLA (16.65.8)scores were improved to 88.87.3 and 31.5±1.9,respectively, at the 2 year follow up. The overall UCLA score showed 1 excellent result and 7 good results. Wethink that symptomatic Os acromiale is a specific disease entity, and open reduction and internal fixation usingtension-band wiring with K-wire is a good treatment modality.