OBJECTIVES: Ankylosing Spondylitis (AS) is a progressive arthritic disease causing pain and severe physical impairments, negatively impacting health-related quality of life. Approximately 127,000 people are estimated to have AS in the UK. Our objective was to estimate the budget impact, over a 5-year period, from the UK National Health Service perspective, of using secukinumab alongside TNF-α inhibitors for adult AS patients with inadequate response to nonsteroidal anti-inflammatory drugs. Secukinumab, the first fully human anti-interleukin-17A inhibitor, is the first licensed biologic alternative to TNF-α inhibitors for AS. METHODS: A budget impact model was developed to compare total drug acquisition and administration costs with and without the introduction of secukinumab. Currently available biosimilar and originator TNF-α inhibitors were included in the analysis. UK population projections were obtained from the Office for National Statistics and published literature. Current and future market share projections were from NHiS and internal Novartis data. The licensed posology was used for all treatments. Drug costs were from the British National Formulary. English administration costs from NHS Reference Costs and PSSRU were applied and assumed relevant for all UK.  Efficacy of secukinumab was assumed to be at least equivalent to the TNF-α inhibitors, based on published indirect comparisons. Therefore, direct and indirect disease-related costs were not included in the model. RESULTS: At list price, the cumulative budget impact of introducing secukinumab is estimated to enable savings of £5.0 million over a 2-year period, rising to £49.2 million over a 5-year period. Sensitivity analyses revealed greater secukinumab usage increased cost savings. A confidential patient access scheme is available to the UK NHS, further increasing potential savings. CONCLUSIONS: