OBJECTIVES:  National Institute for Health and Care Excellence guidance recommends that patients with rheumatoid arthritis in England receive the anti-TNF with the lowest acquisition cost. In practice other non-cost factors may influence treatment selection, such as patient characteristics, hospital characteristics, and changes in regional rheumatology clinical guidelines. This study aimed to identify and quantify the non-cost factors which influence the probability of anti-TNF choice for patients with rheumatoid arthritis in England. METHODS:  Data from 1,066 patients receiving anti-TNF therapies (between 2009-2014) across 34 hospitals in England were taken from a national register held by the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate. Multinomial logistic regression identified which factors influenced the probability of receiving one of five recommended anti-TNFs. Missing data were handled by multiple imputation. Sensitivity analyses assessed if results were robust to using the imputed data and to predefined independent variables. RESULTS:  Greater disease severity increased the probability of choosing etanercept by 5% (p=0.06) and reduced the probability of choosing an older monoclonal anti-TNF (infliximab and adalimumab) by 5% (p=0.06). A 10-year increase in age increased the probability of receiving etanercept by 6% (p=0.00) and lowered probability of receiving infliximab and adalimumab by 6% (p=0.00). Socioeconomic factors had a large influence on treatment selection, with retired patients and patients in a couple being less likely to receive etanercept by 16% (p=0.04) and 18% (p=0.01) respectively. Substantial heterogeneity was observed between hospitals’ probability of choosing certolizumab pegol and golimumab. CONCLUSIONS:  Non-cost factors were found to affect the probability of anti-TNF choice, suggesting that practice may deviate from recommended national guidance. There was some evidence of inequity in treatment selection from the observed influence of factors reflecting socioeconomic status. Strategies to improve prescribing may be needed when deviations from guidance lead to a more expensive (and not cost-effective) anti-TNF being chosen.