Upper urinary tract obstruction in children caused by Candida fungus balls

2 children with upper urinary tract obstruction from Candida fungus balls are reported. A presumptive diagnosis, made on the basis of clinical and radiological findings, was confirmed by microscopic examination of urinary sediment. Medical treatment was successful in both patients. Since Candida infections can occur in patients with altered host resistance, this should alert clinicians to the possibility of fungal involvement when radiolucent filling defects are found in the renal pelvis. Such a presumptive diagnosis can then lead to a correct approach with conservation of renal function.