Six children (1 month to 5 years old) with DIC were treated with bolus injection of AT-III concentrates and/or continuous heparin infusion. In one case, when AT-III concentrates were administered without heparin, the platelet count was normalized in accordance with a rise in the plasma AT-III level. In the other children, who were treated with both AT-III concentrates and heparin, most of the abnormalities in coagulation studies were normalized within 5 days in four of five cases. These findings suggest that the administration of AT-III concentrates may significantly enhance the therapeutic efficacy of heparin, and that the use of AT-III concentrates with heparin is a safe and effective regimen for the treatment of childhood DIC.