Physicians understand the importance of prompt diagnosis and therapy of venous thromboembolism. This is a common and potentially deadly disease. Many patients may have no symptoms of this disorder, yet face a significant risk of serious complications if undiagnosed and untreated. Venous duplex ultrasonography has become the diagnostic test of choice for deep venous thrombosis. Quantitative d-dimer levels may be very helpful in establishing the diagnosis of venous thrombosis. Helical (spiral) computed tomographic scans have replaced nuclear medicine ventilation-perfusion imaging for pulmonary embolus. So, the evolution of diagnostic methods has helped to identify patients with venous thromboembolism at an earlier stage of the disease. Treatment of venous thromboembolism has rapidly evolved over the past 40 years. Patients are often treated with subcutaneous low-molecular-weight heparins as outpatients, rather than admitted to hospital for continuous intravenous infusions of unfractionated heparin. This change in practice grew from a body of scientific literature supporting this advance.