Heparin, low molecular weight heparins, warfarin and aspirin are all effective antithrombotic agents, but each has limitations. Newer antithrombins have been developed to try to overcome these limitations by targeting different steps in the coagulation process. The roles of established and newer antithrombins were discussed at the joint annual scientific meeting of the Haematology Society of Australia and the Australasian Society of Blood Transfusion [Sydney, Australia; July 1998].