The concept of vesicoureteral reflux (VUR) as a consequence of a congenital anomaly of the vesicoureteral junction have undergone changes owing to the finding that such children may have a lower urinary tract dysfunction, which produces a high intravesical pressure and consequently a predisposition for VUR. We investigated relationship of VUR and urodynamics. The urodynamics was investigated by pressure-flow-EMG study in 132 children with primary VUR and 162 refluxing units. Only 33 (25.0%) patients had normal urodynamic finding. The most frequent pathological finding was overactive bladder (OAB), found in 59 (44.7%) children, followed by dysfunctional voiding (DV) in 25 (18.9%) children. The children with VUR grades I and II had higher percentage of pathological urodynamic findings than children with VUR grades III and IV. OAB was more frequent in children under 5 years of age, with unilateral and lower grades VUR. It was found equaly in children with and without uroinfections. DV was more frequent in children older than 5 years, with bilateral VUR, higher grades VUR and uroinfections. The results of our study show that the children with VUR have high incidence of urodynamic disoders and indicate the possible role of urodynamic dysfunction in the pathogenesis of VUR, especially the mild ones. They also indicate the need for incorporating urodynamic investigation in the evaluation of children with VUR.