Gallbladder varices were correctly diagnosed by color Doppler sonography and computed tomography during arterial portography (CTAP) in two patients with portal vein thrombosis. One patient with multiple hepatocellular carcinomas showed extrahepatic and intrahepatic portal vein occlusion by a tumor thrombus. The other patient, with liver cirrhosis, had a portal vein thrombosis. Color Doppler sonography clearly showed the portal vein occlusion, cavernous transformation of collateral veins, and gallbladder varices that drained into the intrahepatic portal venous branches. The intrahepatic portal venous branch, connecting to the gallbladder varices, exhibited reverse flow from the periphery to the hilum of the liver. CTAP also demonstrated gallbladder varices communicating directly with the intrahepatic portal vein branches in both patients. Gallbladder varices developed as a venous collateral because of extrahepatic portal vein occlusion. Color Doppler sonography and CTAP are useful for detecting these varices and planning biliary surgery in patients with portal vein thrombosis.