The safety of low platelet thresholds for prophylactic transfusions was retrospectively evaluated in 673 children with various thrombocytopenic disorders. In patients with idiopathic thrombocytopenic purpura and X linked thrombocytopenia the threshold for the use of platelet transfusion was based on bleeding events rather than platelet count. In children with hypoproliferative thrombocytopenia and Wiskott - Aldrich syndrome, prophylactic platelet transfusions were used when the platelet count was <= 5000/ mu l in stable patients and > 10,000/ mu l in cases of bleeding or infections. The restrictive policy of platelet transfusions was shown to be proved safe in many thrombocytopenic disorders.