We evaluated retrospectively the incidence and prognosis of bacteremias after bone marrow transplantation treated in protected environment with intestinal decontamination. Bacteremias are more frequent during the extreme granulopenia (55% of the patients) than during recovery of granulocyte counts greater than 500/mm3 (35% of the patients). Gram + organisms are more frequently responsible of bacteremias (80%), mainly Staphylococcus epidermidis and Streptococci. Mortality is low (7%) and related to additional factors like GVH, resistant leukemia. These data invite to develop new approaches of prevention of bacterial infection, with measures possibly efficient on Gram + organisms.