Aneurysm of the portal venous system, a localized fusiform or saccular dilatation, is a rare clinical abnormality. Most aneurysms are located in the extrahepatic segment and rarely in intrahepatic branches. Portal vein aneurysms are usually uncomplicated and asymptomatic and detected incidentally during diagnostic work-up. We describe a case of a bleeding intrahepatic portal vein aneurysm studied with ultrasonography, color Doppler, computed tomography, and percutaneous transhepatic portography in a noncirrhotic patient. Although there are 43 published cases of portal vein aneurysm in the English-language literature, neither rupture and spontaneous thrombosis of an intrahepatic portal vein aneurysm nor its nonsurgical conservative treatment has been reported.