Brain and urinary tract function have been studied in a group of 128 geriatric patients with established urinary incontinence. Median age was 79 years. About half suffered from dementia. A group of 27 continent patients of similar age and cognitive status was used in some comparisons. It was expected that impaired voluntary control of voiding (urge incontinence) would be associated with particular aspects of cognitive impairment and dysfunction of specific regions of the brain. Comprehensive investigations, including 24 h monitoring of incontinence, videourodynamic testing, cognitive testing and SPECT brain scanning, demonstrated that genuine urge incontinence could be proven in half of the patients and was frequently accompanied by reduced sensation of bladder filling, especially in males. Genuine urge incontinence with reduced bladder filling sensation led to greater urine loss than other types of incontinence. Overall, cognitive function was slightly more impaired in patients with genuine urge incontinence, but the strongest and most specific association was with impaired temporal orientation. Genuine urge incontinence with reduced bladder filling sensation was associated with global underperfusion of the cerebral cortex and more specifically, with underperfusion of the frontal areas of the brain, especially on the right. These results are consistent with PET scan observations of Blok et al. (Brain 1997;20:112-121), which show that areas in the right anterior cingulate gyrus and right inferior frontal gyrus are involved in voluntary voiding of normal males.