The findings of the videourodynamic (VUD) assessment of the vesicourethral dysfunction of 103 children with neurological disease are described. Detrusor-sphincter dyssynergia was the main determinant of voiding efficiency and the most important cause of impaired renal function. Storage efficiency was mainly determined by the behaviour of the bladder neck during the filling phase. The response to treatment of the child's incontinence was largely determined by the detrusor compliance. Detrusor contractility was found to be of 2 types distinguishable by several physical and functional characteristics rather than by amplitude alone. This may be of more than just academic and semantic importance. VUD studies are essential if conservative treatment modalities are to be rationally and selectively employed.