New markers of intravascular activation of coagulation have been developed, based on advance in our understanding of the biochemistry of the haemostatic mechanism. These are sensitive methods for measuring of peptides liberated with the generation of thrombin (factor IX activation peptide, factor X activation peptide, peptide F1 + 2), for measuring concentration of enzyme-inhibitor complexes (eg. thrombin-antithrombin III-TAT complexes), as well as for investigating the effect of thrombin on fibrinogen (fibrinopeptide A-FPA) or on protein C (protein C activation peptide). Studies employing these markers indicate that a state of hypercoagulability can be detected in the blood of humans prior to the appearance of thrombotic phenomena. However, further studies will be required to determine whether these methods can identify individuals who are entering a clinically relevant hypercoagulable state as well as to monitor an antithrombotic treatment.