BACKGROUND: Persistence on-treatment with antimuscarinics in patients with overactive bladder (OAB) is reported to be sub-optimal. This retrospective, longitudinal, observational cohort study assessed treatment persistence with beta3-adrenoceptor agonists (i.e. mirabegron) and antimuscarinics, both classes of OAB pharmacotherapy, in patients with OAB in Spain. METHODS: Adults who received mirabegron or an antimuscarinic in routine clinical practice (1 June-31 October 2014), were identified from anonymised prescription data within the Spanish Cegedim Electronic Medical Records database. The primary endpoint, treatment persistence (time to treatment discontinuation [TTD] and the proportion of patients remaining on-treatment after 12 months), was unadjusted for potential confounders. Multivariate Cox regression models of persistence, adjusted for baseline characteristics, were used to compare differences in treatment groups. Adjusted subgroup analyses (target OAB drug, age, treatment status and sex) and sensitivity analyses (extending the time used to define treatment discontinuation from 30 days [base-case] to 45, 60 or 90 days without prescription renewal) were also performed. RESULTS: Overall, 1798 patients received mirabegron (N = 1169) or an antimuscarinic (N = 629); the mean age was 66.42 years. Median TTD was longer for mirabegron versus antimuscarinics (90 vs 56 days) and a higher proportion of patients who received mirabegron were persistent after 12 months (20.2% vs 10.2%); multivariate analyses indicated significantly greater persistence with mirabegron versus antimuscarinics (hazard ratio [HR]: 1.52; 95% confidence interval [CI]: 1.37-1.70; p < 0.001). Significant differences were also observed in subgroup analyses of mirabegron versus individual antimuscarinics (median TTD: 90 vs [range] 28-60 days; HR range: 1.21-2.17; p = 0.013) and in all other subgroups assessed (p < 0.001). Sensitivity analysis showed that the median TTD for mirabegron increased by up to 31 days, and was significantly longer versus antimuscarinics across all adjusted periods (HR range: 1.43-1.53; all p < 0.001). CONCLUSIONS: Patients with OAB in Spain who received mirabegron experienced longer persistence on-treatment than those who received antimuscarinics and the proportion of patients persistent on-treatment at 12 months with mirabegron was two-times higher versus antimuscarinics. These data may provide strategic insights for clinicians and policy makers involved in the management of OAB.