The aim of this study was to evaluate the usefulness of cystoscopic injection of Botulinum-A toxin (BTX) in the detrusor wall in the treatment of children with decreased bladder capacity due to neurogenic bladder. The prospective, randomized non placebo controlled trial is conducted in our institution since year 2006 with the approval of the local Ethics Committee. 556 cystoscopic injections of BTX were performed in 141 children with neurogenic bladder in age 1 to 18 years. In all cases decreased bladder capacity and bladder overactivity with urine incontinence were estimated. The pre-and post-treatment evaluations included determination of urinary continence status, bladder function in frequency/volume chart of catheterized urine and in urodynamic studies. Parameters measured in urodynamic investigations included maximal cystometric capacity, detrusor reflex volume, maximal detrusor pressure. Parameters were analyzed before the cystoscopy and during the follow-up examinations in 5 age groups. Values of all measured parameters improved significantly and equally after therapy in every from 5 age groups. The results obtained from the study confirmed that endoscopic administration of BTX improves function of urinary bladder in children with neurogenic bladder, and the method represents an alternative approach to conservative treatment and surgical augmentation.