In this review we summarize the recent innovation of botulinum-A neurotoxin (BoNT-A) injections in the bladder as a potential new treatment option for idiopathic detrusor overactivity, refractory to conventional anticholinergic medication. BoNT-A is produced by Clostridium botulinum and consists of a 150-kDa neurotoxic protein that has the ability to cleave proteins within the nerve terminal. BoNT-A is thereby able to prevent acetylcholine release at the presynaptic membrane, resulting in a chemodenervation of the detrusor muscle after intravesical injection; this can reduce symptoms in patients with refractory idiopathic detrusor overactivity. BoNT-A intradetrusor injections might be an alternative to invasive surgery for patients in whom conservative measures and anticholinergic treatment have failed. Clinical studies with different dosages and injection protocols show success rates of 60-96% for neurogenic and non-neurogenic detrusor overactivity, with wide variations in the duration of response. The drug is still under development for the indication of idiopathic detrusor overactivity, and is under ongoing investigation for long-term efficacy and safety.