This Review Article by Jhang well summarizes the recent advancement for the use of intravesical botulinum toxin injection for the treatment of bladder pain syndrome/interstitial cystitis, as well as the potential mechanisms underlying the therapeutic efficacy of the botulinum toxin treatment, such as peripheral desensitization, reduction of apoptotic changes in urothelial cells and suppression of bladder inflammation. Although some studies showed therapeutic efficacy of botulinum toxin for bladder pain, frequency, bladder capacity and symptom score in bladder pain syndrome/interstitial cystitis patients, larger-sized, randomized trials with a placebo control are definitely required to confirm the efficacy. Also, the methods of botulinum toxin treatment including dosage, injection site/number and treatment interval vary among studies, and need to be standardized.