The diagnosis of a metastatic kidney tumor arising in a 2-month infant is discussed between atypical mesoblastic nephroma and clear cell sarcoma. The precocity of distant metastases, their location in bone marrow, liver and thoracic soft tissues, and their association with myelofibrosis set up an original clinical presentation which seems to have never been described elsewhere. Treatment strategy with surgery of the primary followed by a polychemotherapy combining vincristin-etoposide-ifosfamide and the short term follow-up are reported.