Children with posterior urethral valves (PUV) are at risk of presenting febrile urinary tract infections (UTI). Circumcision has been shown to decrease the number of febrile UTIs in healthy children. The effect of circumcision on the number of UTIs in boys with PUV has not yet been studied. Through a prospective randomised trial of children with posterior urethral valves the investigators wish to determine the effect of circumcision on the risk of presenting febrile UTIs. One group will be on antibiotic prophylaxis alone and the other will be on antibiotic prophylaxis plus circumcision performed at the time of valve resection. Both groups will be followed for two years, with clinical examination at 1, 3, 6, 12, 18 and 24 months. A DMSA scan will be performed at 1-2 and 24 months and biological renal function will also be monitored. The relative risk of presenting a febrile UTI in each group will be determined. Clinical, radiological and antenatal data concerning each child will be analysed. At 24 months follow-up, an "impact on family scale" survey (IOFS) will be proposed parents.