The Sheffield RA health economic model has been used in several published cost-effectiveness analyses in both the UK and internationally to evaluate different treatments for patients with RA. This article presents the key methods and assumptions that underpin the model, including justifications for using an individual patient sampling methodology, and why the model has used the HAQ to track disease activity. The article also details how trial and observational data are used in the model to address specific questions. The model has been used to support health policy in both the UK and internationally, although the limited evidence still provides a challenge when using an economic model to determine the cost-effectiveness of RA treatments. The results of analyses using the Sheffield RA model are presented. The limitations of the model are discussed, and improvements are continually required to provide a model that is appropriate to address health economic questions in the future. The Sheffield RA model continues to be used and refined, and allows health economic questions to be answered using a transparent and flexible modelling methodology.