Differences in the triggering levels for red blood cell (RBC) and platelet (PLT) transfusions were analyzed in association to the amount and total costs of transfusions and the number of febrile episodes during childhood acute lymphoblastic leukemia (ALL) treatment. Transfusions are given with hemoglobin (Hb) < or =90 to 100 g/L and PLT count < or =20 to 30 x 10(9)/L in Tampere, and with Hb < or =80 g/L and PLT count < or =10 x 10(9)/L in Turku. Median pretransfusion PLT count was 48 x 10(9)/L in Tampere, and 16 x 10(9)/L in Turku. The number and costs of PLT transfusions were 35% higher in Tampere. Median Hb before transfusion was 95 g/L in Tampere, and 77 g/L in Turku. The costs of RBC transfusions were 29% lower in Turku as child units (90 mL) were preferred. The number of RBC transfusions was associated with the treatment protocol (P=0.001), and PLT transfusions with the treatment protocol (P<0.001) and the treatment center (P=0.04). The number of febrile episodes was associated with the treatment protocol (P=0.03), and age at diagnosis (P=0.07). Lower trigger levels did not cause more delays or complications in treatment. Clinical trials are, however, necessary to determine optimal criteria for supportive blood transfusions in childhood cancer patients.