We report an 8-year-old girl with a Ewing's sarcoma in the right proximal ulna. The patient presented with pain in her right elbow, and plain radiographs showed destructive changes with a periosteal reaction in the proximal third of the ulna. A biopsy confirmed the diagnosis of Ewing's sarcoma. For preoperative chemotherapy, the patient received two courses of vincristine, doxorubicin and cyclophosphamide alternating with high-dose ifosfamide. MRI and angiography demonstrated that the chemotherapy was effective and therefore the patient underwent wide local excision of the tumor and reconstruction of the elbow joint using a vascularized fibular graft. Pathological examination of the resected specimen showed no evidence of viable tumor cells. After surgery, the patient received three courses of chemotherapy consisting of the same agents as those for the preoperative chemotherapy. Four years after surgery, there is no evidence of local recurrence or distant metastasis. Furthermore, the grafted bone is extending favorably and the patient has excellent function with active movement of the elbow.