The effect of terodiline, a drug with both anticholinergic and calcium antagonistic properties, was studied in vitro on muscle strips from the urinary bladder of children and in vivo in children with diurnal enuresis. Terodiline inhibited all muscle activity in the urinary bladder strips whether induced by nerve stimulation or by drugs with different mechanisms of action. In most children treated the daytime enuresis disappeared completely, with a larger amount of urine at micturition and a lower voiding frequency. Cystometry indicated increased functional bladder capacity and decreased premicturition pressure.