Purpose : The purpose of this study was to evaluate clinical efficacy of the arthroscopic anterior acromioplasty for the treatment of chronic impingement syndrome of the shoulder. Materials and Methods : Between July 1995 and December 1997, twenty seven consecutive shoulders of 26 patients with chronic impingement syndrome of the shoulder were treated by arthroscopic anterior acromioplasty. The patients who had severe osteoarthritis of the shoulder full thickness tear of the rotator cuff, and nonoutlet impingement were excluded. The clinical results were evaluated by using UCLA shoulder rating scale. The average follow-up was 2years 3months(range, 1year 7months to 3years 1 11months). Results : Twenty three patients$(85.2\%)$ were rated as excellent or good results, while four patients$(14.8\%)$ were fair. Twenty six cases$(96.3\%)$ were satisfied with the results of the operations, while one case$(3.7\%)$, who had Parkinsonian syndrome, ossification of posterior longitudinal ligament(OPLL) of the cervical spine, and spinal stenosis of the 5th and 6th cervical spine was not satisfied. Conclusion : Arthroscopic anterior acromioplasty was an effective treatment method, especially for relief of pain, for the treatment of chronic impingement syndrome of the shoulder. If the patient has the combined lesions in the cervical spine and the shoulder, and systemic lesions, these lesions may influence the results of treatment after operation, and cause the unpredictable results.