20 children with severe cerebral palsy and history of urinary incontinence and recurrent urinary infection underwent radio--and neuro-urologic evaluation. Vesico-ureteral reflux was found in 7 patients. In 9, who had presented episodes of urine sub-retention, a urodynamic study demonstrated detrusor muscle hyperreflexia in all, deficit of vesicourethral sensation in 5 and detrusor-sphincter dyssynergia in 2. These functional findings are compatible with an upper motor neuron lesion, and may be the cause of episodes of altered bladder emptying, and consequently, urinary infection.