Nineteen consecutive patients treated surgically for meso-os acromiale and subacromial pathology were reviewed retrospectively, with a mean length of follow-up of 40 months (range, 24-94 months). Of the patients, 11 (58%) were treated with acromioplasty in the presence of a stable os acromiale; 8 patients (42%) underwent open reduction-internal fixation for an unstable and painful os fragment. Of the 19 patients, 8 (42%) with an os acromiale had an associated full-thickness rotator cuff tear. Overall, only 10 of 19 patients (53%) achieved a satisfactory result. All 8 patients (100%) treated with open reduction-internal fixation achieved union of the os fragment, although only 3 (37.5%) achieved a satisfactory result. Of the 11 patients who underwent acromioplasty, only 7 (64%) achieved a satisfactory result. The outcome of surgical management of symptomatic meso-os acromiale with concomitant rotator cuff pathology was satisfactory in 4 of 8 patients in our study group. The rate of satisfactory results was similar in patients with (50%) and without (55%) associated rotator cuff tears. When we analyzed our results to exclude workers' compensation patients, 80% achieved satisfactory results (compared with only 22% in our workers' compensation group).