Congenital interruption of the inferior vena cava is an uncommon vascular anomaly. In this setting, the appearance of deep vein thrombosis is very rare because associated azygous or portal continuation develops as a collateral system for venous return. The authors present a case of infrahepatic interruption of the inferior vena cava in a 21-year-old man who presented with symptoms of deep vein thrombosis. Clinical features and prognosis of this entity are discussed.