The authors studied 24 girls with distal urethral narrowing at voiding cystourethrography. Their observation seem to confirm that the distal urethral stenosis is generally functional, because often an anatomical obstruction can not be detected with the bougie a boule calibration. The urodynamic and urovideocystographic methods of study allow to differentiate three types of functional urethral stenosis that are not detectable with the radiologic examination alone. The physiopathologic mechanism of the obstruction is the condition for a successful pharmacologic treatment of these small girls.