Urinary tract infection(UT1) is one of the major bacterial disease of children that causes morbidity and inconvenience ot many patients were related to recurrent vesicoureteral reflux. radiological examinations of the 72 patients of urinary tract infection(UT1) who were visited to Seoul Paik Hospital from Jan. 1st 1986 to Jul. 30th 1989, were analysed in this study. US was used as an initial study in all patients who showed acute stage of UT1 and followed by IVP, VCUG, 99mTc-DMSA scan for vesicoureteral reflux or renal scarring. If US showed obstructing lesion, no further study was performed. The results were as follows : 1. US is valuable as a screening procedure during the first UT1 in congenital abnormalities and in particular obstructive lesions that require surgery. 2. A normal Us in a child older than 5 or 6 years is meaningful as an investigation in the group of the first documented UT1 uncomplicated. 3. Vesicoureteral reflux, a major factor leading to parenchymal damag in young children can not be detected reliably by US. If the US is suggestive of vesicoureteral reflux, this should be confirmed by VCUG and 99mTc-DMSA scan for renal scarring. If the US is normal or eqivocal in recurrent infection and unexplained persistent clinical findings, this should be followed by VCUG and 99mTc-DMSA scan.