From 1987 to 2001, 181 revision arthroplasties of the knee have been performed in our clinic: 162 aseptic and 19 septic loosenings. The most encountered conditions requiring revision include aseptic loosening, instability, surgical technical failure, infection and mechanical failure including polyethylene wear. In 122 cases we had a signiþcant loss of bone at the femoral and/or tibial side. The experiences of reconstruction in this group will be presented. For the reconstruction of the large contained and uncontained defects, structural allografts, bone chips and morselized bone have been used from our own bonebank (femoral heads). In all of these 122 cases we used at least a half femoral head up to þve femoral heads in very severe cases. To get a sufþcient exposure, a long tubercle osteotomy was necessary in 65% of the cases. A rectus snip was used in 11 cases. Primary stability is mandatory to get a good result. For that reason a very complete modular system is required, including extension rods and the possibility of posterior stabilized and (semi)constrained prosthesis. To obtain primary stability of the femoral component, at least one intact femoral condyle is necessary; for the tibial component at least 65% circumferential cortical support of host bone is needed. Of course there have been complications. Out of this group of 162 aseptic loosenings we encountered 19 major complications: infection 4, woundnecrosis 5 (gastrocnemius ßap 4, amputation 1), loosening of the tibial component 4, loosening of the tubercle osteotomy 3, patellaluxation 2, lesion of the popliteal artery 1. All of these cases have been reoperated: The 4 infected cases needed a multistage procedure: one patient with loosening of the tibial tubercle (traumatic) has been operated 3 times until good consolidation and reasonable function. The amputated patient (81 years old) walks around with crutches. The used technical procedure has proven to be very promising. In experienced hands there is almost always a solution for the loss of bone by allograft boneplasty. Only in the case of a major soft tissue problems, inadequate extensor mechanism or incurable infections, the alternative of arthrodesis should be considered. Revision arthroplasty of the knee is a continious technical adventure and should therefore be performed in specialised centers.