In a recent multicentre double-blind randomized study of men aged ≥50 years with lower urinary tract symptoms suggestive of BPH, administration of either placebo (n = 94) or onabotulinumtoxinA (n = 374) into the prostate transition zone resulted in significant improvements in International Prostate Symptom Score, prostate volume, and maximum flow rate. No significant difference was observed between treatment and control groups owing to a large placebo effect from the injectable therapy.