The primary aim was to assess patient-reported outcomes following a humeral diaphyseal fracture. The secondary aim was to compare the outcomes of patients who achieved union after initial management (operative or non-operative) with those that achieved union after nonunion surgery. From 2008–2017, 291 patients (mean age 55yrs [17–86], 58% [n=168/291] female) were retrospectively identified and available to complete a survey. Sixty-four (22%) were managed with primary surgery and 227 (78%) non-operatively. Outcomes (QuickDASH, EQ-5D, EQ-VAS, SF-12) were obtained at a mean of 5.5yrs (1.2–11.0). After initial management, 229 patients (79%) united (n=62 operative, n=167 non-operative) and 62 (21%) developed a nonunion (n=2 operative, n=60 non-operative; p<0.001). Fifty-two of 56 patients (93%) achieved union after nonunion surgery. The overall mean QuickDASH was 20.8, EQ-5D 0.730, EQ-VAS 74, SF-12 PCS 44.8 and MCS 50.2. Patients who united after nonunion surgery reported a worse functional outcome (mean QuickDASH 27.9 vs. 17.6, p=0.003) and health-related quality of life (HRQoL; mean EQ-5D 0.639 vs. 0.766, p=0.008; EQ-VAS 66 vs. 76, p=0.036; SF-12 PCS 41.8 vs. 46.1, p=0.036) than those who united primarily. When adjusting for confounders, union after nonunion surgery was independently associated with poorer function (difference in QuickDASH 8.1, p=0.019) and HRQoL (difference in EQ-5D -0.102, p=0.028). Humeral diaphyseal union after nonunion surgery was associated with poorer function and HRQoL compared to patients who united primarily. Targeting early operative intervention to patients at risk of nonunion may have an important role, given the potential impact of nonunion on longer-term outcome