Elevation of platelet reactivity plasminogen activator inhibitor, fibrinogen, von Willebrand's factor, and factor VII have been reported to increase myocardial infarction risk. Myocardial infarction and sudden cardiac death are more frequent in the morning when platelet activity is increased and fibrinolysis is decreased. Reduction of recurrent myocardial infarction by aspirin and coumadin suggests causal roles for platelet activity and coagulation. Increases in viscosity and decreases in anti-thrombin III and Protein C have been linked with increased thrombosis. Despite these findings, a coherent picture of these disparate hemostatic indices as cardiac risk factors has yet to emerge.