A temporary arthrodesis of the knee, using an intramedullary Küntscher rod and bone cement, was carried out in 76 patients after resection of tumours of the distal femur or proximal tibia. In contrast to primary arthrodesis with bone grafting, this procedure allows the patient to bear weight on a stable limb a few days after operation, reduces the risk of infection and avoids the negative effect of chemotherapy on graft incorporation. In 12 cases (16%) the implant failed mechanically by fracture, or by bending or migration of the rod, at from 13 to 54 months after operation. Deep infection occurred in 11 patients (14%). A second reconstruction was carried out in 14 patients, 10 using Kotz prostheses and 4 arthrodeses with bone grafting. The operation we describe has advantages for patients with high grade tumours which require chemotherapy and resection-arthrodesis of the knee joint.