Botulinum toxin (BTX) is one of the most potent biological toxins yet described and is natively produced by the Gram-positive anaerobe Clostridium botulinum. Since the first therapeutic experiments in the 1970s, the medical applications of BTX have become myriad and it now plays an essential role in treating neuro-urological conditions. The first complete description of the clinical effects of ingested BTX , then described as “sausage poison”, was published in a case series in 1820 by German physician Justinus Kerner. He was also the first to envisage a potential therapeutic use for the toxin. The causative organism of botulism was identified in 1895 by Emile van Ermengem, and initially dubbed Bacillus botulinus. Purified BTX was isolated in 1928 by Herman Somner, and the first therapeutic use in humans to treat strabismus was performed by Alan Scott in 1980. The use of BTX in urology was pioneered by Dennis Dykstra in Minneapolis, who published a case series of 11 patients with spinal cord injury and detrusor-sphincter-dyssynergia who were treated with intra-sphincteric injection of BTX. This was successful in reducing post-void residual volume, urethral pressure and episodes of autonomic dysreflexia but generated significant urinary incontinence and is no longer routinely used. The first use of intradetrusor injections of BTX for neurogenic detrusor overactivity was reported by Brigitte Schurch in the early 2000s. This was followed up in 2011 by Francisco Cruz in the first multicentre randomised placebo-controlled trial and BTX was approved by the FDA for this indication the same year. There is now emerging interest in the use of BTX for patients with bladder pain syndrome/ interstitial cystitis.