Any child with urinary tract infection needs a radiologic work-up to determine his or her potential risk for sustaining renal damage. VCUG, either fluoroscopic or isotopic, should always be performed. If the infection responds to treatment and the VCUG is normal, ultrasonography should be performed. However, when the VCUG demonstrates reflux, radionuclide scan or, less preferably, excretory urography is indicated to assess renal parenchymal damage and function. When a urinary tract infection does not respond to treatment, ultrasonography or CT scan should be obtained to check for renal or perirenal abscess. If the findings are normal, medical treatment to control the infection is indicated. Further evaluation of the urinary tract may be temporarily delayed. In an infant with urinary tract infection and sepsis, renal ultrasonography is indicated. If the sonogram is normal, VCUG can be delayed until the infant responds to medical treatment. If ultrasonography is abnormal, VCUG and radionuclide scan such as 99mtechnetium DTPA with furosemide to evaluate gross morphology and function should be obtained. Complicated medical problems, such as urinary tract infection in combination with a history of intravenous drug abuse or with findings of fever and a mass, deserve immediate evaluation with ultrasonography or CT scan. A patient with fever of unknown origin and normal urine culture should have a radionuclide scan using gallium67 citrate or indium111-tagged leukocytes, both of which can demonstrate an extrarenal or unsuspected intrarenal site of infection. A variety of imaging modalities are available today for investigating urinary tract infections in the pediatric patient. Used intelligently, singly or in combination, these examinations provide information for the clinical evaluation as well as short-and long-term management of infections, their causes and complication, and their effect on renal function.