A number of neurological disturbances occur during the treatment of childhood malignancies with cytotoxic drugs like vincristine, methotrexate, cytosine-arabinoside, cyclophosphamide, asparaginase and others. Neurological complications range from peripheral neuropathy, myopathy, myelopathy to encephalopathy with methotrexate induced encephalopathy leading to permanent brain damage or death in most cases. Irradiation of the brain can produce transient or permanent brain damage by a direct effect on nervous tissue and by altering the blood brain barrier or the blood circulation. The many conflicting reports concerning the quality of life of long-term survivors of childhood leukaemia do not give sufficient data for final conclusions. The experiences we have encountered over the past ten years seem to confirm the optimistic echo from others. There is, however, an urgent need for a prospective study to answer the all important question: will a child suffering from leukemia emerge physically and mentally unharmed after long and aggressive treatment?