Review of the histological sections of the tumours of 889 patients from the files of the SIOP Nephroblastoma trials and studies has revealed 23 cases with a distinctive growth pattern. Due to the similarity of the histological structures with the architecture of adenofibroma (fibroadenoma) of the ovary we have called this type: nephroblastoma with fibroadenomatous-like structures (NFS). We have studied the clinical and histopathological factors and correlated them with recurrence-free survival and actuarial survival and compared them with the whole series of SIOP Nephroblastomas. This subtype appears to be a distinctive clinicopathological entity with favourable prognosis.