During 1968-77, 572 consecutive children with one or more positive urine cultures who were referred by their family doctors to one paediatric surgical outpatient clinic were investigated and prospectively recorded. An abnormality requiring treatment was found in 45%. The yield of positive findings and need for operation were greater in those referred after one infection than in those with recurrent infection. Among those under 2 years old 90% had an abnormality. One third of children with vesicoureteric reflux showed renal scarring at the time of first attendance. The results of medical and surgical treatment over five to 15 years of follow up were analysed. They emphasised the importance of culturing the urine whenever there may be urinary infection in a child and of investigating immediately those with a positive urine culture.