Over the last 8 years 64 cases of bladder hyperactivity have been subjected to bladder transection. The patients seleced have been mainly adult enuretics, but have also included some others with daytime bladder hyperactivity without nocturnal incontinence who had failed to respond to medical and simple surgical procedures. A bladder capacity greater than 400 ml under general anaesthesia was used as a major criterion in selecting the cases for operation. The operation was very successful in the enuretic syndrome where the daytime symptoms or urgency and urge incontinence were severe. Other patients who had frequency, urgency and urge incontinence without demonstrable neurological or urological abnormalities also responded well.