Sodium valproate is one of the most commonly used drugs to treat epilepsy. However, there is growing evidence that valproate can cause renal tubular injury in children, and there are increasing reports of valproate-induced Fanconi's syndrome where the renal tubules lose their ability to reabsorb electrolytes, urea, glucose and protein. In this review article we attempt to bring together all of the studies conducted to date on the effects of valproate on renal function in epileptic children. The research is generally considered in two themes; the first comprises studies which indicate subclinical tubular injury measured by renal enzymes such as N-acetyl-β-D-glucosaminidase (NAG), and the second comprises clinical reports where Fanconi's syndrome has occurred. This article goes on to analyse the current data and draws on recurring patterns to suggest that a specific subpopulation of severely disabled epileptic children may benefit hugely from the close monitoring of enzymes which are indicative of renal tubular injury, particularly NAG or in the very least periodical urinalysis.