Presentation of one case of Wilms' tumour (nephroblastoma) in a 40-year old woman with clinical and investigational findings common to renal cells carcinoma. Wilms' tumour of the adult is susceptible to the same therapeutic approaches and surgical procedures as applied to childhood's tumours. The most useful prognostic factor is tumoral stage. The presence of anaplasia outside the kidney or a predominant blastemous component qualify the tumour as of "unfavourable histology" rendering it sensitive to the same treatment and prognosis than renal sarcoma. The remaining tumours, gathered under the global heading of "favourable histology", receive a much less aggressive therapy, and the predominant histological component (epithelial, muscular, etc.) does not modify the therapeutic approach.