Rhabdoid tumor of the kidney (RTK) is a quite rare malignant neoplasm of early childhood. It has a very unfavourable prognosis, since it tends to give early metastases and shows a poor response to chemotherapy regimens. We report a case of an infant with RTK, who had a rapidly progressive course. Based upon our case and the review of the literature, we would like to stress the importance of a differential diagnosis with another kidney cancer, namely Wilms tumor, which is more frequent and has by far a better prognosis.