For the comparison of long-term outcome of the management of medical or surgical treatment of children with severe vesicoureteral reflux (VUR), children aged <11 years with non-obstructive grade III/IV reflux, previous urinary tract infection (UTI) and glomerular filtration rate (GFR) >or=70 ml/min per 1.73 m2 body surface area were recruited, and 306 were randomly allocated to receive antimicrobial prophylaxis or ureteral reimplantation. Primary endpoints were new renal scars and renal growth. Follow up, originally planned for 5 years, was extended to 10 years for 252 children, 223 of whom had follow-up imaging. Up to 5 years, 40 new urographic scars (medical 19, surgical 21) were seen. Between 5 years and 10 years, only two further scars were observed. Renal growth and UTI recurrence rate were similar, except that medically treated patients had more febrile infections. There was no difference in somatic growth, radionuclide imaging or renal function. A GFR <70 ml/min per 1.73 m2 was found in only one patient. Three patients developed hypertension requiring treatment. We conclude that, with close supervision and prompt treatment of recurrences, children entering the study with GFR >or=70 ml/min per 1.73 m2 progressed remarkably well under either medical or surgical management, emphasizing the importance of continued supervision and the entry level of renal function.