AbstractStimulation and lesion experiments in the pontine tegmentum of 34 cats, with urodynamic measurements both pre‐ and peroperatively and during up to 4 months of follow‐up, have confirmed the existence of two different brainstem regions concerned with lower urinary tract function. In the dorsolateral pontine tegmentum, a compact, dorsomediolaterally located M region, corresponding to Barrington's micturition centre, reacts specifically to electrical stimulation, causing prompt relaxation of the anal and urethral striated sphincters followed after about 2 s by detrusor contraction, as in normal micturition. Bilateral lesions in this M region lead to a 2–9 week period of urinary retention, during which detrusor activity is depressed and the bladder capacity increases. Stimulation in a larger, more diffuse, more laterally located L region elicits sphincter activity: contraction of the striated urethral sphincter together with an increase in the anal‐sphincter EMG, or relaxation of the striated urethral sphincter together with either a decrease or an increase in the anal‐sphincter EMG. Provided lethal respiratory complications can be avoided, bilateral lesions in this L region lead after a few days to a state, lasting up to 2 months, in which there is urinary incontinence accompanied by a decrease in the bladder capacity and detrusor overactivity. Neither type of lesion leads to true detrusor‐urethra dyssynergia. However, because the amplitude of anal‐sphincter EMG sometimes increases when the striated urethral sphincter relaxes, observations of the anal‐sphincter EMG can misleadingly suggest dyssynergia. Brainstem mapping of the results of stimulation suggests a motor pathway running from the M to the L region and another descending caudally from the L region. The observations suggest that the M region forms a true micturition centre, facilitating the detrusor voiding contraction and also (via the presumptive connection with the L region) ensuring synergic sphincter relaxation. The L region appears not only to relay this voiding sphincter relaxation, but to be responsible for control of the pelvic floor and its sphincters in general, and for helping to maintain urinary continence.