Sixteen patients with advanced giant cell tumors presenting at the knee were treated with complete tumor resection and reconstruction using fresh osteochondral allografts. All patients had one or more of the following indications for tumor resection (as opposed to curettage): tumor recurrence, pathologic fracture, or destruction of the subchondral bone plate. At the 3-15-year follow-up period (mean, 9 years), two grafts have been revised to second fresh grafts because of fracture and one graft has been converted to an allograft-implant composite reconstruction. One joint was fused because of late infection. Functional assessment was carried out in 13 patients, and 8 were good or excellent, 4 were fair, and 1 was poor. The authors conclude that the fresh osteochondral allograft is a viable treatment alternative to prosthetic arthroplasty in advanced, benign, aggressive bone tumors.