Introduction: Radiation induced necrosis and resultant pathologic fracture of the clavicle may follow radiation treatmentof malignant bone and soft tissue tumors. Partial excision of the clavicle, although frequently recommended, may result in persistant pain, weakness, instability, and brachial plexopathy. Clavicle reconstruction is a reasonable alternative. Previously reported methods have been problematic, including use of vascularized fibula or rib, or reconstruction with Dacron mesh with or without bone graft. We describe the use of a free vascularized corticoperiosteal flap as an alternative in these difficult problems. Methods: Two patients with radiation-induced pathological clavicle fractures were treated with free vascularized corticoperiosteal bone flaps. These included a 36 year old female, treated for dermatofibrosarcoma protuberans overlying the left anterior shoulder and clavicle, and a 55 year old male with a metastatic squamous cell carcinoma to the left neck. Both were treated by surgical excision of the tumor and subsequent radiation therapy. Spontaneous pathologic fractures occurred 30 and 9 months afterwards, respectively and remained ununited for 12 and 9 months, until the flap procedure. Preoperatively, both patients complained of limited shoulder motion, and rest and activity-related pain. Imaging studies and surgical inspection both demonstrated atrophic nonunion and avascular changes. At surgery the clavicle was reduced and stabilized with compression plating. A free vascularized corticoperiosteal bone graft was harvested from the medial femoral condyle, based upon the descending genicular arteriovenous pedicle. The flap was wrapped around the clavicle, and microvascular anastomoses performed to the thoracoacromial trunk. Vessel patency checks and a bleeding flap surface confirmed successful transfer. A shoulder immobilizer was used for 6-8 weeks. Passive ROM exercises were then begun. Results: Healing was confirmed by tomography at 5 and 7 months, respectively. No donor site morbidity other than transient medial knee pain was seen. The function of the upper extremity was remarkably improved at final follow-up two years later. Conclusion: Vascularized free corticoperiosteal bone flaps are ideal in the clavicle. The flap is thin, and able to be wrapped around the clavicle without visible bulk. It enables clavicular healing at one bone contact site, and avoids the difficulties of interposing, fixing and healing a bridging vascularized structural graft. The technique of periosteal grafting is ideally suited to chronic nonunions without substantial bone loss, but with poor chances of healing on their own. Rapid subperiosteal new bone and improved local blood flow serve to correct many of those changes attributed to radiation necrosis of bone.