The clinical records and computerized tomography (CT) scans of 14 patients who presented with pyelonephritis to the Children's Hospital of Buffalo between 1976-1985 have been reviewed. The CT findings were as follows: multifocal pyelonephritis (6), lobar nephronia (6), focal pyelonephritis (2). All patients were treated with intravenous antibiotics, and none was surgically drained. Significant underlying diseases were present in 8 patients: diabetes (6), von Gierke disease (1), hepatorenal syndrome (1). The diabetic children tended to have focal disease. Ten voiding cystourethrograms were performed and only four demonstrated reflux. All children became afebrile within a few days. Lobar nephronia was as clinically responsive as pyelonephritis to antibiotic therapy. Urine cultures were most often positive, although there was 1 patient in each category with negative cultures. Blood cultures were rarely positive in any group. Gram negative organisms predominated. CT scanning in children with clinical acute pyelonephritis reveals three major imaging patterns. While distinct radiographically, they behave in a similar clinical manner. Lobar nephronia does not imply a worse clinical prognosis. Intravenous antibiotic therapy alone was adequate for all patients.