BACKGROUND: Acute anterior shoulder dislocation is the commonest type of shoulder dislocation. Subsequently, the shoulder is less stable and more susceptible to re-dislocation, especially in active young adults. OBJECTIVES: We aimed to compare surgical versus non-surgical treatment for acute anterior dislocation of the shoulder. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register (August 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2003), MEDLINE (1966 to September week 3 2003), EMBASE (1988 to 2003 week 39), the National Research Register (UK) (Issue 3, 2003), conference proceedings and reference lists of articles. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing surgical with conservative interventions for treating acute anterior shoulder dislocation. DATA COLLECTION AND ANALYSIS: Selection of the included trials was by all three reviewers. Two reviewers independently assessed methodological quality and extracted data. Where appropriate, results of comparable studies were pooled. MAIN RESULTS: Five studies were included. These involved a total of 239 young (mainly aged around 22 years) active and mainly male people, all of whom had had a primary (first time) traumatic anterior shoulder dislocation. Methodological quality was variable, but notably there was insufficient information to judge whether allocation was effectively concealed in all five trials. Two trials, involving 115 participants, were only reported in conference abstracts.One trial involving military personnel reported that all had returned to active duty. Another trial reported similar numbers in the two intervention groups with reduced sports participation, and a third trial reported that significantly fewer people in the surgical group failed to attain previous levels of sports activity. Pooled results from all five trials showed that subsequent instability, either redislocation or subluxation, was statistically significantly less frequent in the surgical group (relative risk (RR) 0.20; 95%confidence interval (CI) 0.11 to 0.33). This result remained statistically significant (RR 0.32, 95%CI 0.17 to 0.59) for the three trials reported in full. Half (17/33) of the conservatively treated patients with shoulder instability in these three trials opted for subsequent surgery.Different, mainly patient-rated, functional assessment measures for the shoulder were recorded in the five trials. The results were more favourable, usually statistically significantly so, in the surgically treated group. Aside from a septic joint in a surgically treated patient, there were no other treatment complications reported. There was no information on shoulder pain, long-term complications such as osteoarthritis or on service utilisation and resource use. REVIEWER'S CONCLUSIONS: The limited evidence available supports primary surgery for young adults, usually male, engaged in highly demanding physical activities who have sustained their first acute traumatic shoulder dislocation. There is no evidence available to determine whether non-surgical treatment should not remain the prime treatment option for other categories of patient. Sufficiently powered, good quality and adequately reported randomised trials of good standard surgical treatment versus good standard conservative treatment for well-defined injuries are required; in particular, for patient categories at lower risk of activity-limiting recurrence. Long term surveillance of outcome, looking at shoulder disorders including osteoarthritis is also required. Reviews comparing different surgical interventions and different conservative interventions including rehabilitation are needed.