Between 1993 and 1999 allogeneic bone marrow transplantation (allo-BMT) preceeded with fractionated total body irradiation (FTBI) together with cyclophosphamide (120 mg/kg m. c.) or etoposide (60 mg/kg m. c.) was performed in 19 children with acute lymphoblastic leukaemia (ALL). In 9 children transplanted for very high risk (VHR) ALL in I CR the probability event free survival at 3 years was 100%, while for 10 children, that undrewent allo-BMT in II CR after an isolated bone marrow relapse or combined marrow-organ relapse the probability of event free survival at 5 years was 57%. None of the children died due to complications related to transplant procedure. Our observations so far, show that FTBI together with Cy or Vp is well tolerated, has very good antileukemic efficacy in children with VHR-ALL in I CR and gives significantly better results than conventional chemotherapy in children with ALL in II CR.