BACKGROUND This review covers two conditions. These are acute fractures and non-union resulting from failed fracture healing. Clavicle or collarbone fractures account for around 4% of all fractures. While treatment of these fractures is usually non-operative, some types of fractures, as well as non-union of the middle third of the clavicle, are often treated surgically. OBJECTIVE To evaluate the effectiveness of different methods of surgical treatment for acute fracture or non-union of the middle third of the clavicle. METHODS We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (to December 2008), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 4), MEDLINE (1966 to December 2008), EMBASE (1988 to December 2008), LILACS (1982 to December 2008), trial registries and reference lists of articles. No language or publication restrictions were applied. METHODS Randomised and quasi-randomised controlled trials evaluating any surgical intervention for treating people with fractures or non-union of the middle third of the clavicle were considered. The primary outcomes were pain, treatment failure and health-related quality of life or shoulder function. METHODS Two authors independently selected eligible trials and three authors assessed methodological quality and cross-checked data extraction. There was no pooling of data. RESULTS Data from three small trials, each testing a different comparison, were included. Two trials had design features that carry a high risk of bias, limiting the strength of their findings. Low-contact dynamic compression plates appeared to be associated with significantly better upper-limb function throughout the year following surgery, earlier fracture union and return to work, and a reduced incidence of implant-associated symptoms when compared with a standard dynamic compression plate in 36 adults with symptomatic non-union of the middle third of the clavicle. One study (69 participants) compared the Knowles pin versus a plate for treating middle third clavicle fractures or non-union. Knowles pins appeared to be associated with lower pain levels and use of post-operative analgesics, reduced incidence of implant-associated symptoms, and shorter operation time and hospital stay. One study (133 participants) found that a three-dimensional technique for fixation with a reconstruction plate was associated with a significantly lower incidence of symptomatic delayed union than a standard superior position surgical approach. CONCLUSIONS There is limited evidence, from single trials only, regarding the effectiveness of different methods of surgical fixation of fractures and non-union of the middle third of the clavicle.