The optimal treatment of grade III acromioclavicular (AC) dislocation is still controversial. Recent studies recommend surgery at that stage whereas meta-analysis favours conservative management. The objective of the present investigation was to analyse a clinical series of non-operated grade III AC dislocations and to determine their functional status. Thirty-five patients treated conservatively with a grade III acromioclavicular dislocation were retrospectively reviewed. Simple shoulder test, Oxford shoulder and bilateral Constant shoulder score were used for assessment. Various predictive criteria of poor outcome, particularly scapular dyskinesis were taken into account for analysis. Overall mean and median Constant Score of the injured side were 92.9 and 94, whilst the contralateral shoulder values were respectively 94.9 and 95 (mean and median scores). Ten patients had scapular dyskinesis. Laterality, shoulder activity and scapular dyskinesis were not statistically related to worse outcome. Twenty-eight (80%) patients resumed normal activity within six months. All but two patients were subjectively very satisfied or satisfied. Conservative treatment provided satisfactory results whatever the shoulder activity. No risk factors were predictive of a poorer outcome. Conservative management should remain the first option to manage these injuries.