Urodynamical study is a serial of clinical test like uroflowmetry, filling cystometry, pressure-flow studies and assessment of urethral closure pressure. These tests include urethral pressure uroflowmetry and also measurement of the leak-point pressure of lower urinary system. UDS is one of the essential clinical studies in children complaining of voiding dysfunction, neurogenic bladder, urine incontinence, enuresis and another lower urinary tract symptom. The aim of proper bladder management in these patients is to maintain the lower urinary tract to have good capacity, low pressure, preventing infection and incontinence. Long term goal is preventing any undue damage to the upper urinary tracts and intact kidneys function. This review article of pedriatic urodynamical study provides a classical diagnostic approach to bladder dysfunctions in children.