A case report is presented of a malignant rhabdoid tumour occurring in the kidney of a 23-month-old boy. Important differences between this and the conventional Wilms' tumour include the histological demonstration of sheets or cords of large cells resembling myoblasts, a tendency to frequent clinical relapse, and a high mortality rate despite multimodal therapy. In this child, an encouraging initial response to pre-operative chemotherapy, followed by surgical excision and postoperative triple chemotherapy, was not sustained. Recurrence of pulmonary metastases did not respond to further chemotherapy and whole lung irradiation.