We report the results of 238 consecutive patients who underwent in total 261 acromioplasties because of chronic rotator cuff impingement. The procedure was performed either in conventional open technique (80) or arthroscopically (181). Two years (1–10) after the operation 68% of the patients treated with the open technique had an excellent or good result compared 82% of the patients treated arthroscopically by an experienced arthroscopic surgeon. Compared to the open technique, the arthroscopic procedure had a statistically significant superior result concerning outcome, operating time and hospital stay. Arthroscopic procedures performed by less experienced surgeons had inferior results.