In order to improve the dismal prognosis of patients younger than 4 years old with medulloblastoma and supratentorial primitive neuroectodermal tumors (stPNET) seven young children were treated with high-dose chemotherapy (HDCT) and autologous stem cell rescue in our center. All patients underwent surgical debulking and standard chemotherapy. None of them received irradiation. The HDCT included busulfan 16 mg/kg, orally over 4 days (from days -5 to -2) in 6 hourly divided doses, and melphalan at a dose of 140 mg/m2 given by intravenous infusion over 5 min on day -1. Three patients additionally received thiotepa 250 mg/m2 given by intravenous infusion daily over 2 days (from day -2 to -1) and two patients additionally received topotecan 2 mg/m2 given by intravenous infusion daily over 30 min for 5 days (from day -11 to -7). Patients' stem cells were mobilized with granulocyte colony-stimulating factor at a dose of 12 microg/kg twice daily subcutaneously for four consecutive days. Cryopreserved peripheral blood progenitor cells were reinfused 48 h after completion of chemotherapy. With a median follow-up of 21 months (range 5-64) five complete responses were observed; one patient had partial response and one had stable disease. There was no treatment-related mortality. The 2 year event-free survival was 71.43 +/- 17%. Therefore we conclude that HDCT as consolidation regimen may improve the cure rates in very young children with medulloblastoma/stPNET avoiding long-term sequelae of radiotherapy.