BACKGROUND There is a lack of consensus on the best management of the acute Achilles tendon rupture. Treatment can be broadly classified into surgical (open or percutaneous) and non-surgical (cast immobilisation or functional bracing). OBJECTIVES To evaluate the relative effects of surgical versus non-surgical treatment, or different surgical interventions, for acute Achilles tendon ruptures in adults. SEARCH STRATEGY We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (July 2009), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2009, Issue 3), MEDLINE (1966 to 20th July 2009), EMBASE (1966 to 2009 week 29), CINAHL (1983 to July 2007) and reference lists of articles. SELECTION CRITERIA All randomised and quasi-randomised trials comparing surgical versus non-surgical treatment or different surgical methods for acute Achilles tendon ruptures in adults. DATA COLLECTION AND ANALYSIS Two review authors independently selected potentially eligible trials; trials were then assessed for quality using a 10-item scale. Where possible, data were pooled. MAIN RESULTS Twelve trials involving 844 participants were included. One trial tested two comparisons.Quality assessment revealed a poor level of methodological rigour in many studies, particularly with regard to concealment of allocation and the lack of assessor blinding.Open surgical treatment compared with non-surgical treatment (6 trials, 536 participants) was associated with a statistically significant lower risk of rerupture (risk ratio (RR) 0.41, 95% confidence interval (CI) 0.21 to 0.77), but a higher risk of other complications including infection (RR 4.89, 95% CI 1.09 to 21.91), adhesions and disturbed skin sensibility (numbness). Functional status including sporting activity was variably and often incompletely reported, including frequent use of non standardised outcome measures, and the results were inconclusive.Open surgical repair compared with percutaneous repair (4 trials, 174 participants) was associated with a higher risk of infection (RR 9.32, 95% CI 1.77 to 49.16). These figures should be interpreted with caution because of the small numbers involved. Similarly, no definitive conclusions could be made regarding different tendon repair techniques (3 trials, 147 participants). AUTHORS' CONCLUSIONS Open surgical treatment of acute Achilles tendon ruptures significantly reduces the risk of rerupture compared with non-surgical treatment, but produces significantly higher risks of other complications, including wound infection. The latter may be reduced by performing surgery percutaneously.