A clinical study of 5 children (3 boys and 2 girls) with primary sterile vesicoureteral reflux is presented. Their ages ranged from 8 to 11 years old. During the same period, we saw 14 children (6 boys and 8 girls) with primary infected vesicoureteral reflux. Their ages ranged from 1 to 13 years old. There were several distinctions between these two reflux groups. Manifestations of the infected reflux group were mainly fever attacks, while those of the sterile reflux group were hypertension, proteinuria and enuresis. The duration from onset to diagnosis was longer in the sterile reflux group because their manifestations did not appear to be severe especially in cases of enuresis. The grade of reflux tended to be more advanced in sterile reflux group. The renal scarrings were identified in all involved kidneys in the sterile reflux, while in 65.2% in the infected reflux group. It is difficult to detect sterile reflux early because the manifestations are not related with urinary tract infection. Recently, reflux nephropathy is a subject of frequent discussion and end stage of reflux nephropathy has been sporadically reported. Therefore, an effort should be made for early detection of sterile reflux. Based on our experiences as well as review of the literature, possible clues to detect sterile reflux are abnormal voiding patterns, such as nocturnal enuresis, incontinence, frequency and so on.