Twenty-seven patients with posterior urethral valves with varying degrees of renal function underwent both intravenous urography (IVU) and DTPA scan during their follow-up. Although the IVU was successful in excluding obstruction in 31 kidneys, the DTPA scan was successful in 43 kidneys. In addition, the DTPA scan provides quantifiable renal function, exposes the child to a lower radiation dose and has no morbidity compared with an IVU. It is recommended that the DTPA scan should replace the IVU for long-term follow-up and that the latter should be reserved for certain problems.