Ten patients with failed total knee arthroplasties and severe bone loss were treated with massive whole distal femur and proximal tibial allografts in combination with prosthetic implants. Fourteen allografts were inserted either as invaginated or segmental grafts and were rigidly fixed to the host bone. Clinically and roentgenographically, 12 of 14 grafts (86%) seemed to have united to the host bone. The average range of motion was 92 degrees. Five patients developed complications; two of these involved the allograft (nonunion and fracture) and two were caused by inadequate healing at the ligament-allograft junction. One patient had a late infection. With careful planning and improved surgical techniques, these complications can be avoided. The massive allograft-prosthesis composite techniques is a viable reconstructive alternative worthy of further clinical trials.