Multilocular cystic nephroma is a rare disease, noninherited benign renal neoplasm occurring in both children and adults. It is necessary to make a differential diagnosis from all renal diseases with a cystic component, such as Wilms tumor, harmatoma or polycystic dysplastic kidney in childhood. There are about only 200 case reports in the world since Walter Edmunds had described it first. We report a case of multilocular cystic nephroma presented with painless abdominal mass, treated with nephrectomy and confirmed with pathology. (J. Korean Soc Pediatr Nephrol 2001 ;5 : 219-24)