We describe two cases of thrombosed extrahepatic portal vein aneurysms diagnosed by sonography, computed tomography, and magnetic resonance imaging. Portal vein aneurysm is a rare clinical entity that has been described as a focal dilatation that can affect intra- and extrahepatic portal branches. Although usually asymptomatic, thrombosis can lead to portal hypertension. Clinical and imaging characteristics are discussed, in addition to a review of the literature.