Urinary tract infections are common during childhood. The association to bladder dysfunction was studied in two different populations of children. First, the prevalence of UTI in 3553 7-year-old schoolchildren with and without incontinence was assessed. Isolated bed wetting was not associated with UTI. In combined night and day wetting or day wetting alone there was a strong correlation to previous UTI. Secondly, the majority of girls with covert bacteriuria had clinical and urodynamic evidence of bladder dysfunction.