BACKGROUND The aim of our study was to evaluate the results of surgical treatment of clavicle non-union after failure of conservative treatment. Our hypothesis was that stable fixation with bone graft derived from local bone stock (fracture site) or the iliac crest was essential to achieve bone union. METHODS Twenty-one patients with a symptomatic middle-third clavicle non-union after failure of initial conservative treatment were included in the study. Delay between the initial fracture and surgery for non-union was 27 months (6-144). In five cases, the non-union was hypertrophic and bone graft was obtained locally from the callus. In 16 patients, the non-union was atrophic. Bone was harvested from the iliac crest as cortico-cancellous graft (7 patients) and cancellous graft (8 patients). One patient refused bone grafting. A 3.5-mm plate with non-locking screws was placed anterior in 12 and superior in 9 patients. RESULTS At 41 months average follow-up (minimum of 12 months), 20 patients were available for review. Bone healing was obtained initially in 15 cases. Six complications required a revision procedure: 3 for infection and 3 for mechanical failure. At last follow-up, 19 patients were satisfied with the surgery. Average Constant score was 84±26 points (7-100), and Quick DASH score 17±22 points (0-91). Radiographic bone healing was obtained in 19 of the cases. CONCLUSIONS Treatment of middle-third clavicle non-union after initial failure of conservative treatment with stable fixation and bone graft is a reliable, well-suited and effective treatment. Our hypothesis was verified. Preoperative evaluation of appearance of the non-union X-rays can be used to determine the type of bone graft needed, but the final decision is often taken during surgery. METHODS Level IV.