Pulmonary embolism is the third most common cardiovascular disease after myocardial infarction and stroke. The death rate from pulmonary embolism exceeds the death rate from myocardial infarction, because myocardial infarction is much easier to detect and to treat. Among survivors of pulmonary embolism, chronic thromboembolic pulmonary hypertension occurs in 2–4 of every 100 patients. Post-thrombotic syndrome of the legs, characterized by chronic venous insufficiency, occurs in up to half of patients who suffer deep vein thrombosis or pulmonary embolism. We have effective pharmacological regimens using fixed low dose unfractionated or low molecular weight heparin to prevent venous thromboembolism among hospitalized patients. There remains the problem of low rates of utilization of pharmacological prophylaxis. The biggest change in our understanding of the epidemiology of venous thromboembolism is that we now believe that deep vein thrombosis and pulmonary embolism share similar risk factors and pathophysiology with atherothrombosis and coronary artery disease.