Portal vein thrombosis may occur in the presence or absence of underlying liver disease, and a combination of local and systemic factors are increasingly recognized to be important in its development. Acute and chronic portal vein thrombosis have traditionally been considered separately, although a clear clinical distinction may be difficult. Gastrooesophageal varices are an important complication of portal vein thrombosis, but they follow a different natural history to those with portal hypertension related to cirrhosis. Consensus on optimal treatment continues to be hampered by a lack of randomized trials, but recent studies demonstrate the efficacy of thrombolytic therapy in acute thrombosis, and the apparent safety and benefit of anticoagulation in patients with chronic portal vein thrombosis.