We treated a Japanese man with Rendu-Osler-Weber disease and a recurrent encephalopathy with hyperammonemia concomitant with recurrent epistaxis, G-I bleeding, congestive heart failure with aortic and mitral regurgitation, and chronic renal failure. At peritoneoscopy, several telangiectasia were noted on the surface of the liver. Angiographical studies revealed widened and tortuous hepatic arteries with early filling of hepatic veins and small pools of contrast medium scattered throughout the parenchyma. The recurrent encephalopathy was attributed to the porto-systemic shunt formed in the liver.