OBJECTIVES: Mirabegron is a first-in-class beta-3 adrenoceptor agonist for the treatment of overactive bladder (OAB) that demonstrated superior efficacy compared to placebo in OAB. The cost-effectiveness of mirabegron 50 mg (MGN) was assessed in comparison with tolterodine ER 4 mg (TOL) in the UK. METHODS: A Markov model was developed to simulate the therapeutic management, the changes in symptoms (micturitions and incontinence), and complications in OAB patients. The model was used to predict costs and QALYs over 5 years in cohorts initially treated with MGN or TOL, followed by antimuscarinics in case of lack of efficacy or adverse events. Transition probabilities and EQ-5D utilities were obtained from regression models, estimated from a P3 randomized controlled trial of mirabegron. Costs were evaluated from the UK National Health Service (NHS) perspective and included drug acquisition, physician visits, pads and botulinum toxin injections. Subgroup analyses were performed for previously treated, treatment naïve, incontinent, female and elderly patients. RESULTS: The MGN strategy was more expensive compared to TOL, with a difference of £37.88 per patient, and produced more QALYs (+0.009 per patient). The incremental cost-effectiveness ratio (ICER) was estimated at £4,386/QALY gained. Results of one-way sensitivity analyses showed that in all scenarios, except one (the transition probabilities between symptom levels of micturition for mirabegron), MGN remained cost-effective or was dominant compared to TOL. Key cost-effectiveness drivers included parameters related to efficacy and treatment discontinuation. Based on the probabilistic sensitivity analysis, the probability of MGN being cost-effective against TOL was 89.4% at a threshold of £20,000 per QALY gained. ICERs in subgroups ranged from £3,091 (female subgroup) to £5,736 (elderly subgroup). CONCLUSIONS: Treatment with mirabegron 50 mg appears to be a cost-effective strategy compared with tolterodine ER 4 mg for the general OAB population and the specified subgroups, from a UK NHS perspective.