Nephroblastoma, a tumour of the kidney, is most often observed in children; it always includes the nephrogenous tissue in any variant of its differentiation. Histogenesis of this neoplasm is multiform and complex. Its development from very immature pluripotential (polypotent) cells (possibly, at the level of blastodermic vesicle) is not ruled out. The histological classification of nephroblastomas, offered by the author, is based on the principles of differentiation of the tumour tissue and on its histogenesis and opens new perspectives for further investigation of neoplasms and for clinico-anatomic collations.