Plastic-reconstructive surgery for upper extremity tumors not only follows the fundamental principles of oncologic surgery, but also requires attention to functional and aesthetic aspects. For soft tissue reconstruction, a variety of surgical options are available, whereas for the reconstruction of extensive bony defects only the free microvascular fibular transplant appears to be a reasonable method. Its advantages are its slim shape and variable length, the possibility of achieving a stable osteosynthesis suitable for early physiotherapy, and low donor site morbidity, even if the fibula is harvested as an osteoseptocutaneous flap. Between 1994 and 2000, five patients underwent a free fibula transplantation for radius reconstruction. In all cases, a two-stage reconstructive approach with initial tumor biopsy was chosen. The resected tumors were two osteosarcomas, one extraosseous Ewing sarcoma, one aneurysmatic bone cyst and one desmoplastic fibroma. Surgical and pathohistological tumor-free margins were achieved in all cases (R(0)). Two patients received an osteocutaneous graft. All grafts were revascularized to the radial artery and subcutaneous veins. The transplanted fibula grafts were between 10 cm and 17 cm in length. All proximal osteosyntheses were performed fibuloradially, the distal stabilizations were fibulo-scapho-lunate (2 x) and fibulo-radial (3 x), depending on the extent of resection. All microvascular transplants survived completely and showed a stable osseous integration, both clinically and radiologically. Depending on the postoperative course, an adapted intensive physiotherapy regimen yielded good or satisfactory function. In the follow-up of up to seven years in one case a tumor recurrence (osteosarcoma, 35 months post-operatively) required forearm amputation. The reconstruction of tumor-associated wide bony defects in the upper extremity with a free microvascular fibula graft allows for a successful therapy with respect to oncologic, functional and aesthetic considerations.