UNLABELLED: Total knee arthroplasty now exceeds total hip arthroplasty as the most commonly performed joint replacement. Projections suggest the need for revision knee arthroplasty in the future will produce an immense economic burden. The excellent cost effectiveness of primary knee arthroplasty has been well established. This article explores the cost effectiveness of revision knee arthroplasty, and makes a comparison of costs between different international health care systems. While revision knee arthroplasty is more costly, technically difficult, and complicated than primary knee arthroplasty, it is still a cost effective means of improving function, pain relief, and quality of life. The role of national arthroplasty registries will be important in guiding decision making toward reducing the requirements for revision surgery. LEVEL OF EVIDENCE: Prognostic study, level II-1 (prospective study). See Guidelines for Authors for complete description of levels of evidence.