Free latissimus dorsi free flaps were used for the treatment of three patients with malignant tumors localized at the distal end of the femur. In ail cases, a knee prosthesis was used after tumor resection. In two patients, the prosthesis was covered with a free latissimus dorsi flap immediately after insertion. In one patient, the exposed prosthesis that was inserted 9 months previously was also covered with a Free latissimus dorsi flap. Histopathologic diagnosis of the tumors was osteosarcoma in two cases and fusiform cell sarcoma in one case. Free-tissue transfers were successful in spite of preoperative chemotherapy and/or radiotherapy. Chemotherapy was started 3 weeks postoperatively in all cases. Patients ambulated 6 weeks after surgery and knee Functions were satisfactory during a 1 year Follow-up.