Deep venous thrombosis and pulmonary embolism cases were identified and verified in order to estimate incident rates of hospitalized venous thromboembolism in the combined ARIC and CHS cohorts. The association of venous thromboembolism was determined prospectively with demographic and lifestyle factors, plasma lipids, medical history, and hemostatic components (including fibrinogen, platelet count, factors VIIc and VIIIc) using existing ARIC and CHS data. A nested case control study was conducted using stored pre-diagnosis blood and DNA specimens to determine the prospective associations of venous thromboembolism with the following: levels of procoagulant or anticoagulant factors and related genetic variants (including factor V Leiden), fibrinolytic factors (e.g., plasminogen activator inhibitor-1) and related genetic variants, markers of thrombin activation, and other potentially important biochemical or related genetic factors (e.g., homocysteine).