Most patients, in particular those with acute leukemias, will require blood transfusions, usually of red blood cells (RBCs) and platelets. The threshold for red cell transfusion depends on the symptoms and indeed, the speed of onset of anemia. The trigger for platelet transfusion is usually less than 10 × 10 9 /L or if there is evidence of active bleeding or infection, when a higher threshold, 20 × 10 9 /L is appropriate. If a patient requires both red cells and platelet support, platelets are administered first to reduce the risk of a further drop in the platelet count. Febrile reactions following transfusions are not uncommon and are usually managed by slowing the infusion and offering patients antihistamines and steroids, which help reduce the reactions.