OBJECTIVES: Relapsing-remitting multiple sclerosis (RRMS), the most common form of MS, imposes a considerable cost burden on healthcare systems.  Glatiramer acetate 20mg/mL, a once-daily injectable disease modifying therapy (DMT), has long-term real-world efficacy (more than two million patient/years exposure) for the treatment of RRMS.  An economic model was developed to estimate the financial impact on the UK healthcare system of switching RRMS treatments from glatiramer acetate to emerging oral (teriflunomide and dimethyl fumarate) and infused (alemtuzumab) DMTs over five years.  METHODS: The eligible patient population in the model was estimated based on RRMS incidence rates, and the proportion of people receiving glatiramer acetate in the UK in 2013 (based on market share data).  Medication costs were derived from British National Formulary list prices, while treatment administration, initiation and monitoring costs were calculated from UK healthcare unit and hospital tariff codes taking account of requirements specified in Summary of Product Characteristics documentation. RESULTS: The model estimated that 5,900 people with RRMS were receiving glatiramer acetate in the UK in 2013, corresponding to 17.8% of those currently receiving DMTs.  Assuming progressive switching within the eligible RRMS population from glatiramer acetate to teriflunomide (from 1–6% in year one to five), dimethyl fumarate (1–6%) and alemtuzumab (1–3%), additional spending of £17.0 million, £65.3 million and £147.6 million over one, three and five years, respectively, was incurred.  This was primarily driven by higher acquisition costs compared with glatiramer acetate.  Administration requirements associated with alemtuzumab, and the initiation and monitoring requirements of the oral DMTs also contributed to additional costs.  CONCLUSIONS: No data exist supporting the clinical superiority – and therefore associated economic benefit – of the emerging DMTs over glatiramer acetate; switching patients from glatiramer acetate to new therapies may be associated with substantial costs for the UK healthcare system.