A heterogeneous group of 20 consecutive patients was treated according to a standardized allogeneic marrow transplantation protocol designed to reduce early posttransplant lethality. In spite of the fact that 13 patients had at least one (10 of them 2-3) risk factors related to high early lethality, only 2 early transplantation-associated deaths occurred (1 GvH, 1 int. pneumonia). The low incidence of GvH II-IV and interstitial pneumonia, as well as the absence of lethal infections observed in our small patient group, is presumed to be due to the rigorous isolation/decontamination conditions, the reduction of radiation toxicity and GvH prophylaxis by cyclosporin A.