Renal invasion by neuroblastoma is probably more common than is generally recognized. In this study, the incidence of renal parenchymal tumor invasion was 20.4% (10 patients) among 49 cases of abdominal neuroblastoma. Generally, the renoinfiltrative neuroblastomas were extensive and had unfavorable histological features as well as lymph node involvement; they were either stage III or IV. Tumor invasion occurred by direct penetration through the renal capsule and/or lymphatic perivascular spread. Imaging studies had 100% sensitivity and 94.9% specificity for detecting renal invasion of neuroblastoma. Surgery/pathology was the standard of reference. Two instances of misdiagnoses of renal invasion were attributed to inadequate resolution of older computed tomography films, partial volume effects, and renal distortion by tumor compression.