Vesico-ureteric reflux and non-neurogenic bladder dysfunction are closely related, although a causal relationship has been established only for severe forms of detrusor-sphincter dyscoordination. There are several urodynamic studies reporting high frequency of bladder instability and/or detrusor-sphincter dyscoordination in children with reflux. The latter includes an element of functional outflow obstruction and is the most serious, since it accompanies kidney damage. When instability is the only urodynamic abnormality damage is absent. There are indications that treatment of bladder dysfunction increases spontaneous resolution of reflux and, furthermore, that bladder dysfunction is a negative prognostic factor following antireflux surgery. Recently also, gross reflux in infant boys was seen to associate with bladder dysfunction in addition to earlier finding of congenital malformation of the ureterovesical junction. However, no comparisons have emerged on the outcome following treatment of bladder dysfunction and following observation only. In conclusion, children with reflux on chemoprophylaxis prior to reimplantation must always be assessed for bladder dysfunction. This is especially important when there are recurrent urinary tract infections.