Primary vesicoureteral reflux is a frequent condition threatening the renal parenchyma. This severe disease can lead to renal dysplasia and scarring. When revealed by acute urinary tract infection, parenchymal damage has, in most cases, already occurred so medical or surgical care comes too late. Ideally, the population should be screened at birth for vesicoureteral reflux, but unfortunately, no biological test is yet available. At the present time, it would be reasonable to propose cystography to "at risk" populations, first in newborns with pyelocaliceal dilation detected antenatally then in siblings of patients treated for vesicoureteral reflux. Bladder dysfunction, also often associated with primary vesicoureteral reflux, should be identified early and treated. Finally there are several, often opposing, patterns of clinical expression. Antenatally detected vesicoureteral reflux predominates in the male population. Congenital parenchymal lesions, even in the absence of urinary tract infection, are associated with a small capacity hyperactive bladder. Primary vesicoureteral reflux in the school-age girl is associated with post-infectious renal scarring and with a large bladder incompletely emptied during micturition. Early diagnosis, screening of high-risk populations and prevention of infection together with better management of bladder dysfunction should help reduce the incidence of parenchymal damage due to primary vesicoureteral reflux.