The aim of this audit was to assess the union rate of humeral shaft fractures treated conservatively in a functional brace in our unit, compared to a “gold standard” of 98% as reported by Sarmiento (JBJS 1977). A retrospective clinical and radiographic review of 155 closed humeral shaft fractures managed with a humeral brace from 2005–2012 was performed. Pathological fractures and patients under 18 were excluded. The mean age was 60 (18–94) with 45 males and 72 females. 15 (10%) patients under 18 and 8 (5%) pathological fractures were excluded; 15 (10%) patients were lost to follow up. Of the remaining 117 fractures, 83 (71%) went on to union and 34 (29%) developed a non-union. Mean time to union was 131 days (47–622). 80% of distal fractures and 75% of midshaft fractures united but only 58% of proximal fractures went on to unite. There was no significant difference in union rates between multi fragmentary (> 3 parts) and simple fracture patterns (69% vs 71% respectively). Our study suggests that a lower threshold for operative intervention of proximal third humeral shaft fractures may be required.