© 2020 by Turkish Pediatric Association.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<0.001). Bladder capacity significantly increased (p<0.001), and filled bladder wall thickness decreased (p=0.007); however, post-void residual volumes significantly increased (p<0.001) at the third month. No serious adverse effects were recorded during tolterodine treatment. The increase in bladder capacity at the third month in the tolterodine group was similar to that in the oxybutynin group (p=0.77), but the decrease in filled bladder wall thickness was significantly greater in the tolterodine group (p=0.019). Conclusion: Tolterodine remarkably ameliorates the clinical symptoms of overactive bladder in a short time, and seems to be as effective as oxybu-tynin for the treatment of overactive bladder in children. Its effect on reduction of bladder wall thickness appears to be superior to that of oxybutynin.