Hemostatic markers are measured when diagnosing cases presenting with either thrombosis or thrombophilia. Decreased antithrombin (AT), protein C and protein S levels, and positive anti-phospholipid antibody findings together suggest a risk for venous thromboembolism (VTE). Increased thrombin AT complex (TAT) and soluble fibrin (SF) levels indicate a hypercoagulable state, and the addition of elevated fibrinogen and fibrin degradation products (FDP) as well as D-dimer suggests the presence of VTE. D-dimer is frequently measured in VTE cases, but this marker is affected by fibrinolysis and requires standardization. The prothrombin time, FDP and fibrinogen are all used in the diagnosis of disseminated intravascular coagulation. Markedly reduced ADAMTS13 level is a useful sign for the diagnosis of thrombotic thrombocytopenic purpura.