Urographic, arteriographic and B-mode echographic findings in a four-year-old girl with tumefactive xanthogranulomatous pyelonephritis are reported. Review of our case and those that preceded it illustrates that when a localized mass in a functioning kidney is encountered radiographically in a child, xanthogranulomatous pyelonephritis should be included in the preoperative differential diagnosis. Nephrectomy may then be avoided.