In a previous study of the radiologic evaluation of children with urinary tract infection it was recommended that IVP be performed in all patients with either abnormal ultrasonographic or voiding cystourethrographic findings. However, the benefit from IVP was believed to be questionable in children with normal ultrasonography findings and vesicoureteral reflux of only a low grade (I or II of V). To gain a better understanding of the need for IVP in the radiologic evaluation of such children, the database was expanded and the findings concerning ultrasonography and IVP were analyzed in 52 children with urinary tract infection and vesicoureteral reflux seen during the last 3 years. Of a total of 72 instances of reflux, 44 (61.1%) were of low grade (I or II), 14 of medium grade (III), and 14 of high grade (IV or V). Of the 44 urinary systems with low-grade reflux, results were as follows: renal ultrasonography appeared normal in 38 and in 34 of these, the IVP also appeared normal; in the other four, only minor and negligible changes were seen with IVP. Surgical intervention was not necessary in any of these 38 urinary systems. In six systems with low-grade vesicoureteral reflux but with abnormal ultrasonography findings, IVP results were also abnormal, and surgery was necessary in two instances. Of the 14 urinary systems with medium-grade reflux, ultrasonography appeared normal in ten but in six of these the IVP appeared abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)