Recurrent medulloblastoma carries a poor prognosis. Long-term survival has been obtained with high-dose chemotherapy with autologous stem cell transplantation and secondary irradiation. A 21-year-old woman with recurrent medulloblastoma after previous chemotherapy and radiotherapy is presented. The patient was treated with high-dose chemotherapy and autologous stem cell transplantation. She developed a severe treatment-related encephalopathy which affected her quality of life and neurocognitive functioning for the rest of her life. Possible causative factors are discussed and central nervous system toxicity by high-dose chemotherapy in brain tumour patients is reviewed. Case reports on severe central nervous system toxicity have been reported, but data from prospective studies on neurocognitive functioning are not available. These data strongly support a systematic long-term follow-up of brain tumour patients treated with high-dose chemotherapy with emphasis on neurocognitive function tests.