Closed reduction and minimally invasive stabilization of proximal humeral shaft fractures with long PHILOS plates. The presented technique enables stable extramedullary fixation of the fractures without affecting surrounding nerves. Proximal humeral shaft fractures that may not be fixed by intramedullary nailing because of a narrow, deformed or occupied intramedullary canal or because of open growth plates. Fractures that may not be reduced adequately by traction or with percutaneous techniques. Furthermore, fractures with delayed or nonunion and pseudarthrosis should not be treated with this technique. An anterolateral delta split approach is used to create an epiperiosteal tunnel along the humeral shaft from proximally to distally. A second incision is made distally at the lateral border of the biceps muscle. The brachialis muscle is dissected longitudinally. The PHILOS plate is twisted so that the proximal part of the plate can be placed laterally and the distal part anterolaterally at the humeral shaft. The plate is inserted into the epiperiostal tunnel and fixed with percutaneous screws. The arm is immobilized in a Gilchrest bandage until wounds are healed. Active-assisted physiotherapeutic mobilization without loading starts on the first postoperative day. Active mobilization starts 8-12 weeks postoperatively. In cases of soft tissue irritation the PHILOS plate may be removed after 1 year. Between 2005 and 2011 a total of 16 patients (8 women and 8 men) were treated with the presented technique. The patients mean age was 61 years. According to the AO classification, five fractures were classified as type A, eight as type B and three fractures as type C. All patients had clinical and radiological follow-up examinations after a mean of 24 months (12-38 months). All fractures showed complete bony consolidation at the final follow-up. The mean Constant-Murley score was 81 points representing 84% of the Constant-Murley score of the healthy contralateral shoulder. The average DASH score was 33 points and the mean SF36 was 85 points.