SummaryThis study has shown that there is a linear relationship between bladder blood flow and bladder pressure. At a bladder pressure of 80 mm Hg (blood pressure in rabbits varying from 90/60100/70 mm Hg) the blood flow in the bladder is minimal.It is suggested that bladder distension at 80 mm Hg in rabbits leads to hypoxia in the bladder wall as a result of the reduced blood flow.Prolonged bladder wall hypoxia occurring as a result of prolonged bladder distension may be responsible for selective necrosis of bladder tumours.