Objective To evaluate the efficacy of transposition of the medial gastracnemius muscle flap in the limbsalvage operation of the proximal tibial tumors. Methods From January 2001 to September 2005, 13 patients (8 males,5 females; aged 14-57 years, averaged 29.7 years) suffering from the proximal tibial tumors were treated with a limbsalvage operation. Among them, there were 4 patients with osteosarcoma, 6 with malignant fibrous histocytoma, 1 with malignant giant cell tumor, 1 with synovial sarcoma, and 1 with Ewing’s sarcoma. According to the Enneking staging system, 1 case was in Stage ⅠB, 9 in Stage ⅡA, and 3 in Stage ⅡB. One or two cycles of neo-adjuvant chemotherapy were used to each of the patients before operation. All of the patients underwent the medial head of the gastrocnemius muscle flap transposition to reconstruct the soft tissues after resection of the tumors and reconstruction of the bone defect by prothesis or bone-graft or the two methods combined. Results The follow-up for 7-47 months (average, 19.2 months) in all the patients revealed that. there was no flap necrosis, no skin necrosis at the incision margins, and no infection or fracture of the implanted bone. The patient with malignant fibrous histocytoma died of systemic metastasis 20 monthsafter operation. The patient with Ewing’s sarcoma had a local tumor recurrence 18 months after operation; though treated with the focal cleaning and the bone cement filling, the patient still developed lung metastasis of the tumor 26 months after operation. The patient with osteosarcoma underwent amputation 12 months after operation because of the tumor recurrence. According to the function assessment by the Mankin system, there were 6 patients who had an excellent result, 4 had a good result, and 3 had a poor result, with a satisfaction rate of 77%. Conclusion The flap transposition of the medial head of the gastrocnemius muscle can reconstruct the soft tissue defect, decrease the local complication rate and improve the clinical outcome of the limb salvage for the proximal tibia malignant tumor.