AIM: Mild antenatal renal pelvic dilatation (ARPD) revealed by prenatal ultrasound (US) raises the question whether or not screening for vesicoureteral reflux (VUR) is mandatory. The aim of our study was to suggest guidelines for postnatal management of infants with mild ARPD defined as an antero-posterior (AP) dilatation >5 and <10 mm. METHOD: Therefore we assessed the value of postnatal US at day 30 to predict VUR, the incidence of VUR at day 30 and the rate of spontaneous resolution at 1 year. Two hundred (200) infants with ARPD were included and had renal US and voiding cystourethrography (VCUG) at day 30. If VUR was present, VCUG was repeated 1 year later. RESULTS: Incidence of VUR was 10% (20/200) at day 30 after birth and only 3% (6/200) 1 year later. VUR at day 30 was twice as frequent in children with postnatal dilatation (11%) than in nondilated kidneys (6%). CONCLUSIONS: Considering the low incidence of VUR at 1 year, screening for VUR in mild ARDP seems not to be justified. However follow-up by US to detect increase in dilatation and clinical monitoring for signs of urinary infection is required.