Mirabegron is a beta-3 agonist used in the treatment of overactive bladder (OAB). Trials have shown reduced side-effects but equal efficacy when compared to anticholinergics. The authors wished to examine patients’ persistence with treatment, in a non-trial setting, over a period of one year. This was a prospective series of 354 patients. Patients all had symptoms of OAB and were assessed in a urogynaecology clinic. Initially patients were followed up after six weeks using various questionnaires (PGI-I, ICIQ-FLUTS and PFDI). One hundred and ninety-six patients at this stage were known to respond to treatment (55% of the original group) and these patients were followed up at one year. One hundred and eighty-four of this cohort of patients responded. Over the year half of patients continued to take mirabegron (49%) with some degree of symptomatic improvement. The remaining patients who stopped mirabegron quoted lack of efficacy (26%), side-effects (10%), no longer required following surgery (29%) as among the reasons for discontinuation. Of the patients still taking mirabegron 37% were taking it in combination with an anticholinergic. Overall, 25% of the original patients were still taking mirabegron at one year. This continuation rate is similar to anticholinergic therapy. The study showed that over time the initial improvement seen with mirabegron in symptom scores deteriorates. The patients who persist with treatment are those in whom improvements in quality of life are sustained.