Overactive bladder (OAB) is a disorder frequently encountered by the paediatric urologist. Morin et al. report the results of the first known study on the efficacy of mirabegron (a β3 adrenoceptor agonist) as add-on therapy in paediatric patients with refractory idiopathic OAB who were already on an optimised dose of single extended-release antimuscarinic medication. β3 adrenoceptor agonists act on the bladder storage phase by relaxing detrusor muscle resulting in an increase in bladder capacity without significant impact on voiding. Combination therapy (solifenacin and mirabegron) has been shown to be efficacious in adults. Thirty-five patients (7 girls and 28 boys) with OAB were recruited. Median age at initiation of mirabegron was 10.3 years (range 5-18). Different combinations and doses of anticholinergic medications (5-10mg solifenacin / 10-30mg oxybutynin MR / 4mg fesoterodine) and mirabegron (25-50mg) were used. It was a non-randomised and uncontrolled study design. Continence improved in all patients. Twelve patients (34%) achieved complete dryness and 23 (66%) experienced a 50–99% reduction in wetting. Urinary urgency was significantly improved with dual therapy. Voided volumes also improved significantly from 50% to 76% of expected bladder capacity. Compliance was excellent. Twenty-eight patients (80%) did not experience any side-effects (S/E). Five patients experienced mild S/E and one moderate S/E. Only two patients discontinued treatment because of S/E (rhinitis) and increased post void residual. The results of this study are exciting and now demand a prospective randomised controlled trial to validate their further use.