Aim Tolterodine is an anticholinergic drug used for the treatment of overactive bladder. We evaluated the effects of tolterodine on clinical symptoms and compared its efficacy with that of oxybutynin in terms of bladder capacity, bladder wall thickness, and post-void residual volume in children with overactive bladder. Material and Methods Twenty-six patients who were treated with tolterodine for overactive bladder (20 girls, mean age 8.0±2.2 years) were evaluated retrospectively. Twenty patients with overactive bladder who had undergone oxybutynin treatment (15 girls, mean age 7.6±1.8 years) served as the control group. Dysfunctional voiding symptom scoring was used to evaluate the clinical response to tolterodine. To investigate the effect of treatment on the bladder, ultrasonographic data at baseline and the third month were compared with the oxybutynin group. Results The dysfunctional voiding symptom scores significantly decreased after the third month of tolterodine treatment (p