After the first ten bone marrow transplantations for acute lymphoblastic leukemia in children, we evaluated the cerebral outcome as severe cerebral complications had occurred in these patients. From these data we deduced a score of risk factors (SRF) encompassing the facts known to cause cerebral damage in leukemia treatment. In the following 13 patients, we lowered, in the individual patient, the SRF. The number of patients with cerebral damage was lower and no cerebral death occurred.