Abstract Background: The first application of Onabotulinum-A Toxin in urology was its injection into the urinary sphincter to treat neurogenic detrusor-sphincter dyssynergia in quadri-plegic men. Since that first report by Dyskatra et al., in 1988, the results of focal Onabotulinum-A Toxininjections into the sphincter, the bladder wall and lately into the prostate have raised the interest of the urology community in this promising new therapeutic modality. This is an evidence-based review of the current indications, techniques and outcomes of Ona-botulinum-A Toxin injections into the urethral sphincter. Aim of Study: We evaluated the effect of detrusor injection of onabotulinum-A toxin into the urethral urinary sphincter in children with bladder-external sphincter dyssynergia to decrease urethral resistance and improve voiding. Material and Methods: Prospective treatment was per-formed in 25 children 4 to 15 years old (mean age 7) with bladder-neck dyssynergia using onabotulinum-A toxin. Pre-operatively all children were evaluated by ultrasound, voiding cystourethrography, excretory urography, magnetic resonance imaging and urodynamic studies, including pressure flow, electromyography and uroflowmetry. Using a rigid pediatric endoscope and a 4Fr injection needle 50 to 100 IU onabotu-linum-A toxin was injected into the external sphincter at the 5 and 7 o'clock positions. Follow-up was 6 to 15 months. Repeat injections every 6 months were given according to the response with a maximum of 3 injections. Results: Immediately after onabotulinum-A toxin injection all except 1 patient were able to void without catheterization. No acute complications occurred. Postoperatively post-void residual urine decreased by 30%, detrusor leak point pressure decreased significantly by a mean ±  SD of 66±18 vs 37±4cm H2O and uroflowmetry showed a marked increase in maximum urine flow of 7±2 vs 17.3±8ml per second. Conclusions: Urethral sphincter onabotulinum-A toxin injection could be considered a reliable treatment modality in children with nonneurogenic neurogenic bladder after the failure of conservative therapy.