The portal-systemic venous shunt is uncommon in patients without portal hypertension. We present two cases of portal-systemic encephalopathy due to extrahepatic shunt without liver cirrhosis and portal hypertension. Two women in their seventies were admitted to our hospital because of recurrent episodes of altered sensorium, drowsiness, slurred speech, disorientation, asterexis and high blood ammonia levels. There was no history of abdominal surgery or abdominal trauma. Clinical examination revealed no signs of portal hypertension or stigmata of chronic liver diseases. Brain CT and MRI scanning were unremarkable except for a high intensity signal in the basal ganglia on T1 weighted MRI images. Laboratory tests were almost normal except for the hyperammonemia occurring on several occasions. There was no evidence of liver cirrhosis by imaging. However, color Doppler showed an extra-hepatic shunt in both patients and pulsed Doppler showed decreased velocity and volume of the portal venous flow. These sonographic findings were confirmed during percutaneous transhepatic portography (PTP). Portal pressures measured during PTP were 9 and 11 mmHg. Needle biopsy ruled out idiopathic portal hypertension and liver cirrhosis. The diagnosis was portal systemic encephalopathy due to extra-hepatic portosystemic venous shunting. Both patients were treated by embolization of the shunting vessel with metallic coils.