Urinary tract infection (UTI) is relatively frequent in children. The younger the child is, the more symptoms are atypical. UTI is often associated with functional or malformative uropathy, such as vesico-ureteral reflux or obstruction. Appropriate imaging studies should be carried out in every infected child. The prognosis of uncomplicated UTI is very good, but is less favorable when the UTI is associated with urological abnormalities. Development of pyelonephritic scars can lead to kidney scarring, for which the occurrence of intrarenal reflux is probably responsible . Short-term treatment is recommended for uncomplicated UTI. Uncomplicated UTI with frequent relapses requires prophylactic chemotherapy; this treatment should also be considered when UTI is associated with vesico-ureteral reflux. Surgery is indicated in the presence of major urological malformations. Whether medical or surgical, the treatment of UTI should be followed by urine cultures whenever the child presents with fever. The antibiotic treatment of acute pyelonephritis must be started immediately, preferentially by intravenous route. A switch to oral treatment can be made after obtaining the results of the antibiogram. UTI represents a major risk in neonates; it should preferably be managed in specialized centers.