Mild to severe postthrombotic sequelae, including chronic pain, edema, and ulceration, arise in one third of patients short after deep vein thrombosis (DVT). Recurrent DVT is closely associated with the development of postthrombotic syndrome (PTS), whereas if the extent and location of DVT might be relevant remains unclear. Chronic venous hypertension and abnormal microvessel or lymphatic function also correlates with PTS. The diagnosis of PTS is based on clinical grounds only if patients report a history of documented DVT; otherwise, objective testing is required. To abate the prevalence of PTS, the best policy is represented by prevention of recurrent thrombosis and use of stockings. Despite a plenty of surgical options, conservative treatment is preferable because half of the patients improve or remain stable during follow-up, provided they wear elastic stockings. Clinical presentation has a prognostic value, as patients with initially severe symptoms enjoy a more favorable outcome than those who progressively deteriorate over time.