Functional bracing has been widely accepted as the gold standard for treating humeral shaft fractures conservatively. We conducted a literature review to verify the efficacy of this treatment method. Sixteen case series and two comparative studies fulfilled the criteria set. Analysis of these clinical studies showed that humeral shaft fractures when treated with functional bracing heal in an average of 10.7 weeks. Union rate is high (94.5%). Statistical analysis showed that proximal third fractures and AO type A fractures have a higher non-union rate although this is not statistical significant. Residual deformity and joint stiffness are considered the main drawbacks of conservative treatment. Angulation--usually varus--rarely exceeded 10 degrees, while full shoulder and elbow motion was achieved in 80% and 85% of the patients, respectively. Nevertheless, in the few studies that subjective parameters such as functional scores, pain and quality of life were assessed results were not so promising.