In spite of its invasiveness, voiding cystourethrography remains the gold-standard examination for detecting vesico-ureteric reflux. The aim of this study was to determine if voiding cysto-urethrography is useful at any pediatric age in girls after a first acute pyelonephritis. 152 patients have been retrospectively studied. Both reflux frequency and grade progressively decreased according to age. Sonography was unable to predict reflux. In more than 3-year-old girls, 8/30 children with reflux had voiding dysfunction. We suggest clinical and/or a flow-metric evaluation for voiding dysfunction prior to voiding cystourethrography. After 9 years, reflux was so rare that voiding cystourethrography should be discussed on an individual basis.