On the basis of 133 cases, the authors analyse the clinical features and the modalities of the treatment of vesicorenal reflux in children under age 2. The number of girls is higher than that of boys. The diagnosis is most often established between 0 and 6 months of age, with a very marked peak between 0 and 1 month. The usual warning sign is a urinary infection with fever. Pyerography is normal in every second case, and retrograde cystography is the key examination, which confirms the reflux and establishes its side and degree (bilateral reflux in 53% of cases, stage II in 48% of cases). 33 children were operated at once. Another 100 first had a medical treatment, ie. urinary antibiotics, on the basis of strict criteria that are listed here. This medical treatment has been very disappointing: 20 children were lost to follow-up and 47 had secondary surgery. When surgery is necessary, advancing plasty according to Cohen's procedure yields excellent results: 98.6% of 76 operations were successful. The authors therefore think that Cohen's procedure is widely indicated, even in children under age 2.