Videourodynamic studies were performed on 57 wet children, 35 of whom were assessed retrospectively and 22 prospectively. Thirty-two studies (56%) were abnormal; detrusor instability or reduced compliance was found in 26, increased bladder sensitivity in 3, detrusor sphincter dyssynergia in 2 and sphincter weakness incontinence in 1. A detailed micturition history sheet and the results of routine preliminary investigations (mid-stream urine and ultrasonography) were used in an attempt to predict the outcome of urodynamics. Since only 5 of the 25 normal studies and 18 of the 32 abnormal studies were correctly predicted, it was concluded that accurate prediction was not possible. Urodynamic investigations are therefore required to identify the underlying cause of wetting and to guide appropriate treatment.