Background: Management of high grade acute acromioclavicular (AC) joint dislocation is considered a surgical dilemma. Open methods of fixation are the gold standard but the morbidities are frequent. The goal of this study was to evaluate the results of arthroscopic fixation of acute high grade (AC) joint dislocation. Methods: A series of 24 patients with acute high grade acromioclavicular joint dislocation were fixed arthroscopically using TightRope device. The study was done between February 2013 and February 2017. The functional outcomes were assessed using Constant-Murley score and University of California at Los Angeles shoulder (UCLA) scale. The preoperative and postoperative means of coraco-clavicular distance were calculated and used for radiological assessment. P-value < o.o5 was statistically significant. Results: The mean followed up time was 23.25 ± 7.1 (12–35) months. There was highly significant improvement in the Constant-Murley score and (UCLA) scale at the end of the follow up period. The coraco-clavicular distance was improved from 21.7 ± 3.1mm preoperative to 10.17 ± 2.3mm postoperative. There were two complications, one case had over correction and the other had mild transient post-operative burning pain along the course of ulnar nerve. Conclusion: Arthroscopic fixation of acute high grade (AC) joint dislocation is safe, minimally invasive technique with satisfactory functional outcomes and low morbidities provided that it is done by surgeons skilled in shoulder arthroscopy. 1. Introduction Acromioclavicular (AC) joint dislocation is a common traumatic shoulder insult with male to female ratio (5:1).1,2 Direct strike to the lateral aspect of the shoulder is the most common mechanism of this injury.3 Rockwood4 classified the (AC) joint disruption into six types according to the direction and the severity. Conservative treatment is indicated in types I and II.5–7 Surgical treatment is recommended for types IV, V and VI and young active patients with type III.8–10 Most of the present studies advocated early surgery for acute type ΙΙΙ injuries in highly demanded patients because it had significant better functional results compared to conservative treatment.11 There are several methods used for fixation like K-wires, hook plate, Bosworth screw, Weaver-Dunn and resection of the lateral end of the clavicle, with no gold standard procedure.10,12–16 Wound healing problems, the need for second operation to remove the hardware, big scar and infection are common problems associated with the