Poor prognosis childhood cancers are mainly metastatic diseases represented by stage IV neuroblastomas developed in children more than one year and metastatic Ewing tumours. These both diseases are chemosensitive but not curable with conventional chemotherapy. In these indications, high-dose chemotherapy with autologous peripheral blood stem cells transplantation is delivered in patients achieving a good partial remission with conventional treatment. The toxicity of these procedures is high but manageable; these approaches have improved the prognosis of these patients.